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Niles® Audio SI-245

Stereo power amplifier

2 Reviews

Item # 190SI245

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Our take on the Niles® Audio SI-245

Multi-room audio systems operate better when you use an amp that offers greater flexibility than a typical stereo amp. If you own a receiver with a second-zone preamp output, the Niles® SI-245 is the perfect power amp for those second-zone speakers.

Multi-room audio systems operate better when you use an amp that offers greater flexibility than a typical stereo amp. If you own a receiver with a second-zone preamp output, the Niles® SI-245 is the perfect power amp for those second-zone speakers.

You get 45 high-current watts RMS per channel and 4-ohm stability — connect two pairs of 8-ohm speakers in parallel without worrying about overloading the amplifier or speakers.


  • discrete, high-current design
  • 45 watts RMS per channel into 8 ohms (both channels driven)
  • 70 watts RMS per channel into 4 ohms (both channels driven)
  • three turn-on modes: music sensing, voltage trigger, and manual
  • dual 5-way binding posts
  • 12-volt control out
  • voltage trigger input accepts 3-30V AC/DC
  • cascade output lets you easily add another amp to your system
  • left and right channel adjustable level controls let you match volume from one room to the next
  • DC, short circuit, and overload protection with automatic reset
  • detachable AC power cord
  • 17"W x 2-5/16"H x 13"D
  • warranty: 2 years

What's in the Box:

  • 2-channel power amplifier
  • 6.3' two-pronged AC cord
  • Instruction manual
  • Safeguards
  • Warranty and registration card

Niles® Audio SI-245 Reviews

Average Customer Review(s):

(2 Reviews)

Niles® Audio SI-250

MDB from Coral Gables, FL on 10/10/2013

Crutchfield Customer Review (What's this?)

I was disappointing when I went online to order a second one of these amps as it showed that they were discontinued. I guess I got the last one of the run. Whining aside, I use this amp to drive 2 Definite 6500 outdoor speakers. feed the NIles through a Sonos Connect (Yes I am addicted to Sonos). The amp has a great feature called "Audio sense". It picks up tiny signals from the RCA input and turns the amp on. IT drives the 6500 pretty loud. Overall I am happy wit the product as it serves it purpose nicely.

Pros: size, audio sense feature, price

Cons: None that I can think of.

Niles® Audio SI-245

Jeff from Chandler, AZ on 11/15/2006

Crutchfield Customer Review (What's this?)

I am have this amplifier plugged into the 2nd Zone output on a Sony STR-DA7100ES receiver. This provides audio to three sets of SpeakerCraft CRS speakers located in other rooms throughout the house.<BR><BR>There is a night and day difference in the quality of the sound and volume levels that can be achieved.<BR><BR>I strongly suggest this unit if you need to send audio to another zone. <BR><BR>The ONLY downside was that this unit is not available with a brushed stainless bezel.




Hands-on research

Product Research



Independent power supply: Each channel is powered from its own independent power supply. This minimizes cross talk.

Independent level controls: Each channel has its own level control allowing you to limit the output and to precisely match the amplifier to the rest of your system.

Three turn-on modes: Three turn-on modes allow you to interface with any kind of system and have the amplifier automatically turn on.

Protection Circuitry: Automatic DC, short circuit and overload protection.

Control Output: A 12 volt DC output allows you to operate voltage-triggered  devices such as motorized screens and curtains.

High quality parts: Uses 1% metal film resistors, high quality capacitors and oversized heat sinks.


Front panel:

  • Master power switch: turns unit on and off
  • Power LED: Illuminates in red when the unit is connected to AC and the master power switch is on.
  • Active LED: Illuminates in green when the amplifier circuitry is turned on by the turn on circuits.
  • Protect LED: Illuminates in red when the unit is turned off by the protection circuitry.
  • Independent left and right level adjustment screws: Allow you to preset the maximum system volume or match levels with another amplifier using a 1/8" slotted screwdriver (not supplied).
Rear panel:
  • Turn-on mode switch: Allows you to select one of three modes.  Constant mode defeats the turn-on circuitry and the front panel master power switch turns the unit on and off.  Audio sense mode turns the amplifier off when no audio signal is present for three minutes and on whenever an audio signal is present.  3-30 volt AC/DC Trigger mode turns the unit off when no AC or DC voltage is detected at the trigger input and turns the unit on when a voltage and a line level audio signal is detected.  
  • 3-30V AC/DC trigger input: 3.5mm female jack for voltage input.  If a unit which outputs 3-30V AC or DC voltage is connected to this input and the turn-on mode is set to Trigger mode the unit turns on when it detects the signal and turns off when the signal stops.  Voltage triggers are supplied by some Niles automated switchers, some video projectors or even a 16 volt Niles AC wall adapter (Niles XF00008).
  • 12 volt control output: Female 3.5mm jack. This jack provides a 12V DC signal used for triggering Niles automated switchers, some motorized screens, curtains, etc.  When the amplifier is turn off this jack stops sending out the 12V DC signal. 
  • Main input: Gold plated RCA stereo input.
  • Main output: Gold plated RCA stereo output (marked Cascade output) which allows you to daisy chain multiple amplifiers.  This output is not buffered so if you want to chain more than 5 amplifiers a buffered distribution amplifier like the Niles ADA-6 is needed.
  • Speaker outputs: Left and right gold-plated 5-way binding posts accept up to 12 gauge bare wire or banana plugs.
  • AC jack: For the supplied AC line cord.


Continuous Average Power Output:

  • 45 watts per channel RMS at 8 ohms
  • 70 watts per channel RMS at 4 ohms
  • Minimum impedance load of 2.67 ohms

Input Impedance: 22k ohms

Input sensitivity: .77V for 8 ohm rated input

Overall voltage gain: 28 dB

Frequency response: Bandwidth limited from 10 Hz to 100 kHz

Total Harmonic Distortion:

  • 8 Ohms: .05% THD from 20 Hz to 20 kHz @ full rated power
  • 4 Ohms: .06% THD from 20 Hz to 20 kHz @ full rated power

Weight: 15 lbs.


The manual recommends at least 5" of free air space above the chassis and that, if the unit is placed in a cabinet, that the rear of the cabinet be opened. 

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