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		 CONGRATULATIONS!   
					Thank you for purchasing the Niles SI-2125, one of the most flexible and   
					convenient amplifiers ever offered. Like all Niles products, the SI-2125 is built to   
					the highest standards of quality control and reliability. With proper installation and   
					operation, you'll enjoy years of trouble-free use.   
					Niles manufactures the industry's most complete line of custom installation   
					components and accessories for audio/video systems. For a free full line catalog write:   
					Niles, Catalog Request, P.O. Box 160818, Miami, Florida 33116-0818   
					TABLE OF CONTENTS   
					INTRODUCTION   
					2 
					3 
					FEATURES AND BENEFITS   
					INSTALLATION CONSIDERATIONS   
					FRONT AND REAR PANEL DETAILS   
					INSTALLATION   
					5 
					9 
					11   
					15   
					16   
					18   
					OPERATION   
					TROUBLESHOOTING GUIDE   
					SPECIFICATIONS   
					The lightning flash with arrowhead symbol, within an   
					equilateral triangle, is intended to alert the user to the   
					presence of uninsulated dangerous voltage within the   
					product’s enclosure that may be of sufficient magnitude   
					to constitute a risk of electric shock to persons.   
					CAUTION   
					CAUTION: TO REDUCE   
					THE RISK OF ELECTRICAL   
					SHOCK, DO NOT REMOVE   
					COVER. NO USER-SERVICE-   
					ABLE PARTS INSIDE. REFER   
					SERVICING TO QUALIFIED   
					SERVICE PERSONNEL.   
					The exclamation point within an equivalent triangle is   
					intended to alert the user to the presence of important   
					operating and maintnance (servicing) instructions in the   
					literature accompaying the appliance.   
					CAUTION: TO PREVENT ELECTRICAL SHOCK, MATCH WIDE BLADE OF PLUG TO WIDE SLOT, FULLY INSERT   
					ATTENTION: POUR EVITER LES CHOCS ELECTRIQUES, INTRODUIRE LAME LA PLUS LARGE DE LA FICHE   
					DANS LA BOURNE CORRESONDANTE DE LA PRISE ET POUSSER JUSQU’AU FOND   
					WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR   
					MOISTURE   
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					1 
				FEATURES AND BENEFITS   
					Real World Power   
					The SI-2125 delivers 125 watts per channel at 8 Ohms, 200 watts per channel at   
					4 Ohms and 300 watts bridged at 8 ohms. You’ll get tremendous bass and dynamics   
					from every pair of speakers powered by an SI-2125.   
					Transparent Sound   
					The audio circuitry of the SI-2125 is constructed using the finest parts available;   
					including 1% metal film resistors, high quality capacitors, and oversized heat sinks.   
					All this attention to technical detail creates a sound that is clear and uncolored with   
					phenomenal imaging.   
					Freedom From Crosstalk   
					Each channel of the SI-2125 is powered via its own independent power supply. This   
					increases the isolation between the two channels, and eliminates cross talk   
					guaranteeing you absolute silence as the backdrop to your music.   
					Current For Reactive Loads   
					The high current design of the SI-2125 assures that even unusual and reactive loads   
					are handled with aplomb. A massive toroidal transformer with two separate windings   
					for each of the power supplies supplies more than ample current to your system.   
					Freedom from Fan Noise   
					The oversized heat sinks inside the SI-2125 allow the amplifier to stay cool even when   
					operating into low impedance loads—without the noise of fan-cooled amplifiers.   
					Independent Level Controls   
					Each channel has its own independent level control enabling you to precisely   
					match the SI-2125 to the rest of your system. The level controls also enable you   
					to limit the volume, preventing abuse of the system.   
					Lifetime Connections   
					The SI-2125 features gold plated stereo inputs, the cascade stereo outputs as well as   
					the five way binding posts are gold plated to ensure perfect connections without   
					corrosion for years to come.   
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					3 
				Turn-On Modes   
					The SI-2125 features three turn-on modes: 1. Music Sense 2. External Voltage Trigger   
					3. Manual Turn-On via the front panel switch. You can configure the   
					SI-2125 to interface with any kind of system and have the unit automatically turn on.   
					Automatic Protection   
					The SI-2125 is equipped with sophisticated protection circuits. In the unlikely event   
					that a problem occurs, the amplifier shuts itself off. When conditions return to   
					normal, regular operation resumes.   
					Status Display for Troubleshooting   
					LED's on the front panel indicate Power, Active Status, and a Protection Warning. With   
					a glance at the front panel, a troubleshooter is quickly provided with key information!   
					Control Output   
					A 12 volt DC output is provided whenever the amplifier is on, allowing you to   
					operate voltage-triggered devices like motorized screens and curtains.   
					Bridged Mode   
					The SI-2125’s can be operated in a bridged mono configuration. In this   
					configuration, it can deliver upwards of 300 watts. Bridged mode is perfect for   
					subwoofer, rock speakers or any applications requiring high power output.   
					Designed and Engineered in the USA   
					Limited two year parts and labor Warranty.   
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					4 
				INSTALLATION CONSIDERATIONS   
					Placement   
					Place the SI-2125 on a flat level surface like a table or shelf. It should be placed   
					upright so that its weight rests on the four attached feet. Placing the weight of the   
					amplifier on the rear or front panel for even an instant will result in damage to the   
					amplifier's connectors and controls.   
					The SI-2125, like any hi-fi component, will last much longer if it is given adequate   
					ventilation for proper cooling. When installing the SI-2125 in a cabinet, be sure that   
					the rear of the cabinet is open to fresh air to provide proper cooling (see Figure 1). If   
					the cabinet’s design will not accommodate an open rear, install two small “boxer   
					fans” to provide continuous air flow into and out of the cabinet (see Figure 2). Place   
					the SI-2125 so that there is at least 7" of free air space above the chassis. If the   
					amplifier is located on a carpeted surface, place a board under the amplifier's feet.   
					Do not block the ventilation holes on the top and bottom of the SI-2125.   
					CAUTION! When using low impedance speaker loads (less than 8 ohms Normal   
					Mode) refer to figure 2 for proper placement.   
					The SI-2125 is equipped with an internal transformer, which generates a powerful   
					magnetic field which could induce hum in a turntable (particularly a turntable   
					equipped with a moving coil cartridge). Do not place a turntable directly above   
					or directly adjacent to the SI-2125.   
					Figure 1   
					Figure 2   
					Boxer Fan (55 CFM)   
					directly centered 7"   
					on top of the SI-2125.   
					Boxer Fan (55 CFM)   
					directly centered 2"   
					behind the SI-2125.   
					Make sure that there is a minimum of 7" of free air   
					space above the amplifier for proper ventilation.   
					If the cabinet rear is not open to fresh air or if you’re using   
					low impedance loads, install two “boxer fans” to provide   
					continuous air flow into and out of the cabinet.   
					Allow a minimum of 2" of depth behind unit   
					to accommodate cables and connectors.   
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					5 
				Turn-On Modes   
					The SI-2125 draws more current than a preamplifier’s switched AC outlet can   
					safely supply. Also, your preamplifier may “thump” at dangerous volumes if the   
					amplifier is already on when the preamp turns on. It is usually best to turn the   
					amplifier on only when it is needed. The Turn-On Mode selector switch gives you   
					three options for turning the SI-2125 on and off.   
					Constant - The auto turn-on circuitry is off. The front panel master power switch   
					operates the amplifier. In is “On”, out is “Off”.   
					Audio Sense - The master switch on the front panel must be in the “On” position.   
					The amplifier is off when there is no audio signal present at either the left or the   
					right input, but the sensing circuitry is on. The turn-on sensing circuitry looks for   
					a tiny amount of audio signal present at any of the audio inputs. If it detects a   
					signal, the amplifier is turned on. Once the audio signal stops, the sensing circuit   
					waits two minutes, then turns the amplifier off.   
					3-30 Volt AC/DC Opto-Isolated Voltage Trigger - The master switch on the front   
					panel must be in the “On” position. The amplifier is off when there is no 3-30V AC   
					or DC voltage detected at the trigger input. Once the sensing circuitry detects a   
					voltage, the amplifier is turned on. Once the voltage stops, the sensing circuit   
					instantly turns the amplifier off. Voltage triggers can be supplied by Niles automated   
					switchers, some video projectors, some surround sound processors, or something   
					as simple as a 16 volt AC wall adapter (Niles XF00008) plugged into the switched   
					outlet of your stereo receiver. DO NOT USE A DC WALL ADAPTER. The long   
					discharge time of the DC adapter’s filter capacitor will delay the turn-off of the   
					amplifier.   
					If you are using a wall adapter or external power supply to provide the trigger, it   
					doesn't have to be very large (a minimum current capability of 2.5 milliamps for a 3   
					volt trigger increasing up to a minimum of 38 milliamps for a 30 volt trigger).   
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					6 
				Bridged Mode   
					The SI-2125’s bridged mode switch allows you to create a more powerful   
					amplifier by combining both channels into one (8 ohm minumum). In the bridged   
					mode, connect the speakers to the left red positive terminal and the right red   
					positive terminal. In the bridged mode the right channel’s red terminal becomes   
					positive and the left channel's red terminal becomes negative.   
					DO NOT USE THE BLACK NEGATIVE (-) TERMINALS. THE SIGNAL IS AT THE   
					RED POSITIVE (+) TERMINALS ONLY.   
					Multiple Speaker Loads   
					The SI-2125 is stable into very low impedance loads. This means you can safely   
					operate three pairs of 8 ohm speakers (a 2.67 ohm load) directly connected to the   
					SI-2125. Note that the SI-2125 does not have on/off speaker switching built in.   
					When the amplifier is on, so are all of the speakers. (for more information on   
					proper amplifier placement, see Installation Considerations on page 5, Figure 2).   
					Niles makes a number of different speaker selection and impedance matching systems.   
					Speaker selection systems allow each pair of speakers to be turned on and off from your   
					equipment location (or even via remote control). That way, you know that the speakers   
					in the bedroom are off so you can avoid waking a sleeping spouse! These speaker   
					selectors provide an easy way to terminate all of the wires for more than three pairs.   
					Testing and troubleshooting a new system is much easier with the individual room   
					labels and on/off switches of a Niles speaker selection system. Additionally, Niles   
					speaker selection systems offer impedance matching features which will allow you to   
					connect up to ten pairs of speakers to your SI-2125 amplifier.   
					TECH TIP   
					Wire size is expressed by its AWG (American   
					Wire Gauge) number. The lower the number, the   
					larger the wire, i.e. twelve AWG is physically   
					larger than fourteen AWG.   
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					7 
				Niles SI-2125   
					Niles HDL-6 Speaker Selection System   
					AMPLIFIER   
					L- R-   
					SPEAKER   
					6 
					SPEAKER   
					5 
					SPEAKER   
					4 
					SPEAKER   
					3 
					SPEAKER   
					2 
					SPEAKER   
					1 
					L+   
					R+   
					L+   
					L 
					- 
					R 
					- 
					R+   
					L+   
					L 
					- 
					R 
					- 
					R+   
					L+   
					L 
					- 
					R 
					- 
					R+   
					L+   
					L 
					- 
					R 
					- 
					R+   
					L+   
					L 
					- 
					R 
					- 
					R+   
					L+   
					L 
					- 
					R 
					- 
					R+   
					ON OFF   
					NILES   
					CONSTANT   
					PROTECTION   
					Niles Audio   
					Corporation, Inc.   
					Miami, Florida USA   
					Speaker selection systems allow each pair of speakers to be turned on and off from your   
					equipment location (or even via remote control).   
					Cable and Wire   
					It will be easier to reconfigure or troubleshoot your system in the future if you   
					label the cables and wires for their destination or source, rather than which   
					terminal of the SI-2125 they are connected to.   
					The SI-2125 connects to your sources via shielded line level audio cables with   
					RCA phono plugs. Use high quality cables with your Niles amplifier for the lowest   
					possible noise and best overall performance. Your Niles dealer can recommend   
					the proper cable.   
					The SI-2125 connects to your speakers using 2 conductor speaker wire. For most   
					applications, we recommend you use 16 or 18 gauge wire. For wiring runs longer   
					than 80 feet, we recommend 14 gauge wire. The binding posts of the   
					SI-2125 will accommodate up to 12 gauge wire. Larger sizes can be accommodated   
					by attaching banana plugs to the wire. Note that the binding posts accept dual   
					banana or single banana connectors.   
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					8 
				Red “Power” LED confirms the amplifier is   
					connected to a live AC power outlet. (and   
					that the master power switch is on).   
					Green“Active” LED lights when the   
					amplifier circuitry has been turned on by   
					the Turn-On circuits.   
					Front panel “Master Power” switch turns   
					off the entire amplifier, including the   
					Turn-On circuitry.   
					The red “Protect” LED indicates the amp has shut   
					down because there is a fault in the speaker, the   
					wiring, or with the SI-2125 itself.   
					Main Inputs enable you to route a stereo   
					line level source to the SI-2125.   
					Cascade Outputs of the main input enable   
					you to daisy chain multiple amplifiers.   
					“Turn-On Mode” switch   
					3.5 Mini Plug socket   
					for voltage input.   
					3.5mm Mini Plug socket for   
					12v DC Control output.   
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					9 
				Level Adjustment screws enable you to preset   
					the maximum system volume (or match levels   
					with another amplifier).   
					Bridge mode switch   
					IEC receptacle for AC   
					power cord.   
					Binding posts for speaker connections.   
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					10   
				INSTALLATION   
					Pg. 11 Setting The Turn-On Mode Switch   
					11 Control Output   
					Pg. 13 Line Level Audio Inputs   
					13 Cascade Audio Outputs   
					14 AC Power plug   
					12 Speaker Wire Connections   
					Setting the Turn-On Mode Switch   
					The SI-2125 has three turn-on modes. Select which mode you desire by sliding   
					the mode switch. See Installation Considerations on page 6 for more information   
					about each of the turn-on modes.   
					Slide the switch with your fingernail or a   
					1/8" slotted screwdriver blade.   
					Control Output   
					This terminal provides a 12v DC signal   
					suitable for triggering Niles automated   
					switchers, some motorized screens, some   
					electric curtain controls, etc. The trigger   
					voltage is present only when the amplifier is   
					active or “on”. When the amplifier turns “off”,   
					the 12 volt signal is off.   
					Using the   
					3.5 mm jack.   
					STEP   
					DESCRIPTION   
					1. Check the requirements of the   
					device you want to control.   
					The control output has a maximum   
					current capability of 12vDC 150 mA.   
					2. Connect the 3.5mm Jack to the   
					control output maintaining proper   
					polarity (tip = +)   
					Niles makes an accessory cable   
					plug FG00724.   
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					11   
				Speaker Wire Connections   
					CAUTION! All speaker wire connections must be made with the amplifier Off.   
					Bare Wire   
					Banana Plugs   
					Unscrew the red or   
					black plastic knob,   
					insert the bare wire   
					end into the opening,   
					and then tighten the   
					knob until the wire is   
					securely clamped.   
					There are many types of   
					banana plugs, some   
					crimp, some solder. The   
					Niles gold banana plug   
					has   
					a 
					quick-connect   
					binding post for the   
					bare wire on the body   
					of the plug. A banana   
					plug is simply inserted   
					into the jack at the   
					end of the amplifier’s   
					binding post. Dual   
					banana plugs will fit the   
					SI-2125 binding posts.   
					STEP   
					DESCRIPTION   
					1. Label all wires.   
					If you label the wires for their destination,   
					rather than which terminal of the SI-2125   
					they are connected to, it will be easier to   
					reconfigure your system in the future.   
					2. Connect one stripped wire end or   
					banana plug to the black terminal   
					and one to the red terminal.   
					A. Split the speaker wire insulation so that   
					at least two inches of each conductor are   
					separated.   
					B. Strip one half inch of insulation from the   
					end of each conductor of the speaker wire   
					C. Attach banana plugs or twist the strands of   
					wire together and insert them into the   
					appropriate binding post.   
					CAUTION- Avoid even a single strand   
					of wire touching the chassis or another   
					connector.   
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					12   
				Line Level Audio Input   
					CAUTION! THE AMPLIFIER MUST BE OFF WHENEVER YOU MAKE CHANGES   
					TO THE INPUT CONNECTIONS.   
					STEP   
					DESCRIPTION   
					1. Label all of the interconnecting   
					cables for the sources they connect to.   
					Use audio patch cables with RCA phono   
					plugs attached to the ends.   
					2. Connect the sources by inserting the   
					RCA plugs into the amplifier’s jacks.   
					Connect outputs from your sources to   
					inputs on the amplifier. Never connect a   
					source or preamplifier’s input (e.g., record   
					inputs) to the inputs of your SI-2125.   
					Cascade Audio Outputs   
					The “Cascade Audio Outputs” enable you to connect another amplifier to your   
					preamplifier output. The connectors are gold-plated RCA phono jacks. Connect   
					them to another amplifier’s inputs with a standard audio patch cable. The outputs   
					are not buffered; if you wish to daisy-chain more than 5 Niles amplifiers you   
					will need a Niles AVDA-3 buffered distribution amplifier. A single AVDA-3 will   
					allow you to daisy-chain 5 amplifiers from each of its 3 outputs, allowing 15   
					SI-2125 power amplifiers to be fed from the same master preamplifier. If your   
					preamp has a vacuum tube output stage, you must use a Niles AVDA-3 to drive   
					more than a single SI-2125.   
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					13   
				AC Power Plug   
					STEP   
					Plug the female IEC socket of the   
					supplied AC cord into the IEC   
					receptacle on the rear of the amplifier.   
					Just like a computer or printer, the SI-2125   
					has an AC cord which unplugs either at the   
					amp or at the wall for your convenience.   
					If you use a grounded power strip, surge   
					suppressor or extension cord, verify that   
					proper ground is maintained.   
					Plug the 2 prong plug into   
					120V 60 Hz wall outlet.   
					The SI-2125 draws   
					approximately 700 watts from an AC wall   
					outlet. Use the auto turn on circuit instead.   
					a 
					maximum of   
					CAUTION! Typically the   
					preamp/receiver’s switched outlet   
					is not rated for a power amplifier.   
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					14   
				OPERATION   
					Power Switch   
					The front panel switch is a master or “vacation” power switch. No matter which   
					turn-on mode you have selected, the master power switch will turn off all   
					circuitry—including the sensing circuitry. If you will not be using the amplifier for   
					an extended period of time, turn the master power switch “Off” (push button   
					switch out). When you would like to return to normal operation, turn the switch   
					”On” (push button switch in).   
					Power LED   
					The power LED indicates that the AC cord is plugged into a working AC power   
					receptacle and that the power switch is in the ”On” position.   
					Active LED   
					The rear panel turn-on mode switch determines when and how the amplifier will   
					turn on. The ”Active” LED indicates that the amplifier is operating.   
					Protection LED   
					The front panel protection LED indicates that the amplifier has been shut down   
					because of either a fault in the wiring or the speaker, or with the SI-2125 itself.   
					Level Adjustment Screws   
					The front panel level adjustment screws allow you to adjust the level of the   
					SI-2125 relative to other amplifiers in your system. Use a 1/8" slotted screwdriver   
					to adjust the screws. If the SI-2125 is the only amplifier in your system, leave the   
					screws at their factory default position (turned fully clockwise).   
					Cleaning and Maintenance   
					The internal parts of the SI-2125 are electronic and require no maintenance.   
					Once a year it is appropriate to twist the RCA connectors on each input to remove   
					corrosion and improve conductivity. You can clean the amplifier with soft cloth or   
					paper towel dampened with water or a mild detergent. Do not use any spray-type,   
					abrasive cleaners on the amplifier.   
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					15   
				TROUBLESHOOTING GUIDE   
					When there is a problem consult this guide first. If the problem persists, or you   
					have additional questions, call your local Niles dealer or Niles Technical Support   
					at 1-800-289-4434. The most common problems relate to hook up. Call from   
					your telephone extension nearest the system.   
					POSSIBLE CAUSES AND TEST PROCEDURE   
					SYMPTOM   
					Short circuit or loose wire at the speaker or   
					No sound on one channel   
					amplifier terminals. Check that the connections are   
					secure and that there are no loose strands of wire   
					crossing from the positive to the negative terminals   
					at the back of the amplifier and /or the speaker.   
					Short circuit or a break in the speaker wire. Dis-   
					connect the speaker wire at both ends, separate the   
					2 conductors at both ends and test with a meter for   
					a short circuit. If there is no short, connect the two   
					conductors at one end and test with a meter for   
					continuity.   
					Speaker is not working. Connect the speaker to a   
					channel that plays another speaker.   
					Audio cable to input is bad. Connect another cable   
					that is known to be good.   
					Audio cable to the main inputs is bad. Connect   
					another cable that is known to be good.   
					No sound on both channels   
					Hum from the speakers   
					Hum may be caused by a ground loop between   
					two of the other components in the system. To test   
					for another ground loop, try reversing the AC plugs   
					of each of the components in the system.   
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					16   
				TROUBLESHOOTING GUIDE (continued)   
					POSSIBLE CAUSES AND TEST PROCEDURE   
					SYMPTOM   
					Check for faulty cables, faulty source material, an   
					ungrounded phono system or a defective component.   
					Hum from the speakers   
					AC power cord must be plugged into a working outlet.   
					Master power switch must be on.   
					Amp will not turn on   
					Bass sound is weak and   
					the stereo image is   
					“phasey” or “blurry”   
					sounding in one room   
					The loudspeakers are wired out of phase.   
					Reverse the connections at the back of one speaker.   
					Make sure that the Bridge Mode Switch is in the   
					stereo position if the amplifier is being used in a   
					stereo configuration.   
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					17   
				SPECIFICATIONS   
					Design Principle   
					Linear voltage/current amplification.   
					Continuous Average Power Output   
					125 watts per channel RMS at 8 ohms.   
					200 watts per channel RMS at 4 ohms.   
					300 watts bridged channel RMS at 8 ohms.   
					Input Impedance   
					18K ohms   
					Input Sensitivity   
					.878V for 8Ω rated output   
					Overall Voltage Gain   
					33 dB   
					Frequency Response   
					Bandwidth Limited from 10 Hz to 100 kHz   
					Total Harmonic Distortion   
					8 Ohms   
					.02% THD from 20 Hz to 20 kHz @ full rated power   
					4 Ohms   
					.02% THD from 20 Hz to 20 kHz @ full rated power   
					Overall Dimensions   
					17" wide 5 1/2" high (including feet) 13-1/8" deep   
					Weight   
					26 lbs   
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					18   
				Niles Audio   
					Corporation   
					
					12331 S.W. 130 Street   
					Miami, Florida 33186   
					Tel: (305) 238-4373   
					Fax: (305) 238-0185   
					©2003 Niles Audio Corporation. Because Niles strives to continuously improve its   
					products, Niles reserves the right to change product specifications without notice.   
					Niles, the Niles logo and Blending High Fidelity and Architecture are registered   
					trademarks of Niles Audio Corporation. Systems Integration Amplifier and   
					BusMatrix are trademarks of Niles Audio Corporation Printed in the Malaysia 9/03   
					DS00354AMY   
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				I N S T A L L A T I O N   
					& 
					O P E R A T I O N G U I D E   
					SI-2125   
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					Systems Integration Amplifier   
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					B L E N D I N G H I G H F I D E L I T Y A N D A R C H I T E C T U R E ®   
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