Fosi Audio M03 200 Watt TPA3255 Subwoofer Amplifier Mini Mono Channel Audio Power Amp for Home Theater Full-Frequency and SUB Bass Switchable with 32V/5A Power Supply

UPDATE: The TAPE out hookup I mentioned below worked great for levels, but TAPE out is, by design, not controlled by the volume knob on my Pioneer receiver, so I had to constantly adjust two knobs, one under my desk at the sub, so not ideal. The solution? I just added a $25 preamp before the FOSI to have excellent subwoofer levels from the Pioneer subwoofer output, plenty of signal now at half volume or less on both the preamp and the FOSI main amp. The preamp is also a simple and excellent little device.https://www.amazon.com/dp/B0945RFJ6Z?ref=ppx_yo2ov_dt_b_fed_asin_titleI went with this preamp instead of some units, like the FOSI preamp, because it does NOT do any RIAA equalization that I did not want to add to the mix.I bought this FOSI to get my 24 year old KLH subwoofer running again.I am very pleased.I was able to remove the plate amp assembly and leave the SW box sealed on the back as it has always been, by the plastic box that had housed the circuitry.I might mount the FOSI in this plastic recess, but for now it sits atop the SW cabinet and if its rubber feet keep it from walking off I will just leave it there for ease of reaching the controls.This tiny powerhouse is driving the 8" KLH speaker to make better sounds and deep vibrations, than it has for years. Gone are the occasional deep pop and rattle sounds that I had thought might mean the speaker cone itself had deteriorated. It turns out the old cone is just fine. The KLH built in amp had apparently been slowly cooking its circuit board for a long time before it gave up completely last week.It looks like a bulging cap and some burned resistors... maybe I will fix that board someday.One word of warning. I was driving the old KLH ASW 100 powered subwoofer with an RCA Y-cable from the low level sub output RCA jack of a 20 year old Pioneer home theater amp. It turns out that the signal level on that jack is too low to get more than just a faint response from this FOSI, even turned up to the max.So don't assume this will be a direct replacement if you have that kind of subwoofer hookup.I ended up driving this FOSI with a dual RCA cable from the tape record outputs of the Pioneer, and I am getting loud, clear and rumbling bass from the FOSI at only about four clicks of the volume knob. The FOSI volume and freq cutoff controls have a nice, subtle, detent feel.

The item was as described and works well. After realizing that that the positive and negative wires were crossed, it was difficult to troubleshoot. A lot of extra wires to get the standalone sub to finally work. But work it as it sounds great.

I brought my gently used, mint condition JBL E150p out of closet storage after years of hibernation (I like to build and try different home subs, passive and powered) to replace my overkill Memphis Audio HPO 15" sealed subwoofer for office audio/HT duty.After a few months of occasional use, the JBL subwoofer amp failed (it is at least 15 years old at this point I think) and not wanting to spend a ton of money or build a case for a larger and bulkier plate amp, I looked across the Googleverse for a budget fix.Knowing marketed power ratings are often the result of creative license, I looked for the most powerful sub amp under $100 that I could find with half decent reviews and a basic but usable functionality.The JBL 10" sub is rated at 150rms/300peak, so the Fosi MO-3 seemed to be the closest realistic option.Installation is simple, build quality (case) is basic but clean. The tactile feel of the knobs is nice as others have mentioned. Having crossover adjustment markings would be nice but not a huge deal.The JBL is a 6ohm sub so theoretically the MO-3 should be sending it around 120ish watts rms at max volume.However I don't think it's remotely close, as the Pioneer AVR I use with this setup has to be turned up nearly twice as loud to get similar sub output. Fortunately I can reduce the satellite speakers volume through the AVR to compensate.However, I already took this into account before ordering the Fosi, and considering that the built in JBL digital amp is 3 times the size of the Fosi with a large power supply, huge capacitors, etc, I wasn't looking for the Fosi to defy science.Overally, it's a nice little amp and I recommend it for someone looking for a budget fix or just for DIY tinkering.Also, a friend of mine bought the 2.1 BT Fosi unit about the same time and loves it, he says it gets pretty loud with his setup, which he's using to power a pair of older bookshelfs and a Definitive Technologies ProSub1000 subwoofer with passive radiator.One last thing, during my testing and playing music, it hasn't gotten hot or cut out so far and as mentioned, it's at max volume, so that's a good sign. Hopefully it lasts...

Works excellent with plenty of power to spare. It has a good, solid sound and a clean tone.