Heres a used Dayton SA240. I am the original owner, its been in the closet for a while and was previously used on an active home theater sub box - it wasnt used aggressively. I powered it up, and connected it to a (unenclosed) speaker at low volume to test for signal output, there is signal and both gain & frequency knobs seem to be doing what they need to do. So I assume all is well, but have not tested this fully installed. I dont have a complete subwoofer/box around to do any more detailed testing but I have a multimeter and can follow directions, if you want something else tested please ask. The face frame is just shy of 10x10 --- the actual recessed area that must fit in a box (IE the hole size) is ~8.5 x 8.5. Sold as-is but for buyers with 10+ feedback if you find theres a problem contact me and we can discuss options. Im not trying to pass of junk, and I cant 100% test it. See me at mercpb síte for best #s Dayton Audio SA240 240W Subwoofer AmplifierThe Dayton Audio SA240 Subwoofer Amplifier generates 240 watts of clean power and behind the less than 10 x 10 faceplate lurks a tiger of a plate amp, ready to unleash its power on your subwoofer driver. This multipurpose subwoofer amplifier can power a variety of subwoofer drivers whether you need it for home theater or pro audio use. The Dayton Audio SA240 includes all the features that you have requested, like a choice of RCA line level or banana jack speaker level inputs and outputs, automatic power-on that is triggered by any audio input signal, and a phase reverse switch to match the subwoofer to your room and your other speakers. A single amp can accept a stereo input signal and combine it into mono, which is optimum for sub bass reproduction. The internal low pass crossover is fully adjustable between 40 and 180 Hz, and of course the amp has built-in protection against internal and external faults. Unleash the beast! Dimensions: 9-13/16 W x 9-13/16 H x 5 D. Cutout dimensions: 8-1/2 W x 8-1/2 H.