Fosi Audio M04 Subwoofer Amplifier for Home Theater Mono Channel Digital Class D Integrated Power Amp for Passive Speakers Subwoofer

Got this subwoofer amp to bypass the amp component of my active subwoofer which died months ago due to a peak in voltage. My amp was those that work in "stand-by" mode, so they are always powered up somehow. Replacing the board with a new one (original) was too expensive, even more expensive than what the sub costed me in the first place, so in order to not throw the box and the woofer cone to the trash, I decided to just rewire things up in order to bypass the sub's integrated amp, so I got this GREAT little FOSI amp to power my "now passive" sub.Things worked great and my sub is now back to life, shining again.The M04 Fosi Amp is a great choice as it is POWERFUL, noiseless (at least to my ear), very small and does not generate any important heat. It comes with a power adapter, so you only need the cables to connect the input signal and the output signal to the passive subwoofer. I used the convenient "bare wire connection" to hook the modified sub to the speaker output of the Fosi Amp. Worked NICELY.Quality of the M04 Fosi AMP is VERY GOOD, in a very neat, compact and ellegant BLACK enclosure. It is definitely worth the money, which is NOT AT ALL expensive, but quality exceeds by far the amount paid for this amp.Until now, i'm really loving it.

The Fosi M04 Subwoofer Amplifier was purchased as part of a computer speaker system in which the original amplifier "died of old age." The speakers were still good so it made no sense to dispose of them. Since it is not being used in a home theater system, I cannot speak to the full 100 watt output capability. My original computer speaker system (Logitech) is a 5.1 system with the amp inside the subwoofer box. I purchased a six channel amp for the surround speakers and this Fosi 04 amp for the subwoofer. All works well together. Listening to pipe organ music, which can put out some big bass sounds, the amp provides the bass that I need. (I do have a good audio system for music.Amazon has the "frequently returned" warning for this item. That's probably because people order without understanding what they need, not because the product is inferior. It produces lows from 20Hz. The item was packaged very well with foam and an attractive box, with a factory seal. I would place this in the excellent category of quality and price. (It's not junk) and has an 18 month warranty. Of course I have decades of experience building electronic devices and knew what I wanted for the purpose and budget

5 stars if they supplied the larger power brick. I bought this because I have another I purchased to replace a blown sub amp. Seeing it is operable in full range mode and always wanting to try mono-blocks I felt this was the cheap way to do it and honestly it was worth it.

Easy to wire and the frequency and volume adjustments work well with good control over the levels. I'm using it to power an old subwoofer that the original receiver died on and the replacement receiver does not have a sub output built in. It brought the old sub back to life, even better than original.

I purchased this to power passive the sub woofer on a Panasonic 3-speaker system I picked up at Goodwill. Great little unit, and powers the sub just fine. It is small, inconspicuous and easy to connect. Plenty of power for my office setup, easy to use and adjust quality and output levels to go along with my listening choices. This unit meets my needs for the speakers I have, and I am not disappointed.

I recently upgraded a low-budget A/V system located in a technically challenging environment - an attached greenhouse with hot tub. The previous system's receiver had a built-in amp. for the passive sub. The "new" (relocated) receiver has only line-level sub outputs, so this amp. was an obvious choice to close the "gap". I can make all the speaker and sub. adjustments including level and cross-over frequency in firmware, but it's quite convenient to have the sub volume easily adjustable on the unit itself as various sources need to be tweaked. As far as I can tell, the input jack is mono only so the mono 3.5mm plug to RCA adapter cable I bought works fine. (The photo the supplier provides in the product description shows a stereo 3.5mm plug at the input and the related consumer questions/answers on this topic are unclear.) When I first connected the system I had no sound out, but the issue was quickly traced to the speaker settings in firmware where I had declared the front L/R speakers as "Large". They need to be set to "Small" to get audio to the sub. I set the sub level in firmware to +5dB and the crossover freq. to 90Hz, but that latter will need some additional tweaking. At first experience the audio is great! Good, thunderous bass without overdriving the sub...more than I expected from this cheap system!. The unit runs cool to the touch and shows no evidence of being stressed in any way. I expect it to last a long time!.A couple of suggestions for the manufacturer: 1) consider using a less bright LED as the power on indicator - the current one is almost blinding in a darkened environment, as others have reported (the LED is dim when the volume control is switched to the OFF position then becomes very bright when switched ON) - and; 2) consider providing a standby mode when no audio signal is sensed (system power-down) like powered subs provide. I guess this latter is moot since the attached power supply would always be active and pulling some minimal power any time it's plugged-in. Otherwise, so far this seems to be a great product that will serve me well for many years...!