Stealth Acoustics Monural Subwoofer Amplifier SA255 MKII

The Stealth Acoustics SA255 MKII is an integrated monaural subwoofer amplifier/crossover system designed as a low distortion power source for Stealth Acoustics invisible subwoofer panels or other un-powered subwoofers.  The SA255 MKII can also be used for full range speakers when the low pass filter is off.

With a full complement of input and output connectors, the SA255 MKII is easily integrated into any audio system. Inputs include RCA line level, balanced XLR line level, and phoenix connector speaker level, all with pass-through capability. The speaker level input/pass-through connections allow the SA255 MKII to feed directly from full-range speaker lines, anywhere in the system.

  • Rack mountable
  • Variable low pass filter
  • Auto On/Standby function
  • Balanced line input and output
  • DC protected fixed high pass filter
  • 12v trigger function
  • Output monitor LEDs


Rack Mountable

(2) RU spaces: 3-1/2” (89 mm)
(*Provided rack ears are removed)

DC Protected

Fixed high pass filter @ 18Hz

Variable Low Pass Filter

50 to 150Hz / 18 dB per octave

Power Standby LED

Red (blue when system is active)


Auto On/Standby Function

Switch selectable on/off

Flexible Inputs with Pass Through

Binding post speaker level inputs / outputs
RCA line level inputs / outputs
XLR balanced line inputs / outputs

Amplifier Output Connector

5-way binding post


Output monitor LED’s

6 level readings

Phase Switch

Low Pass Filter on/off Switch

Fan Cooled

Automatic – 8 speed stages

110v and 220v Input Voltages

TypeMonaural Subwoofer Amplifier/Crossover
Mono Power Output250 watts @ 8 < 0.05 THD_x000D_
350 watts @ 4 < 0.05 THD
Total Harmonic Distortion<0.05 @ 1 watt 4 / 100Hz
Signal to Noise Ratio86 dB below rated output
Low Pass Filter50Hz – 150Hz / 18 dB per octave
High Pass Filter18Hz / 30 dB per octave (fixed)
System Impedance8Ω nominal, 4Ω minimum
Current Draw6.2A @ 350W/4 – 115VAC/60Hz
Width19” (482 mm) with ears
Height3-1/2” (89 mm) without feet
Depth13-5/8” (345 mm) without knobs
Weight31.3 Lbs. (14.20 kg)