Fosi Audio V3 Stereo Amplifier Home Audio 300 Watts x2 Power TPA3255 Class D Mini Speaker Amp 2 Channel Audio Component for Passive Bookshelf Tower Speakers Desktop Home Theater with 48V Power Supply

Don't believe the 300 watt claims of the manufacturer. (I don't know why they just don't rate the amp with RMS real world specs). Still the Fosi Audio V3 is an excellent amplifier when paired with the optional 48V power supply, although it increases the cost. With the supplied stock power supply, the amp can deliver about 30 watts of real power and with the 48V power supply it can deliver about 80 watts of unadulterated bliss. The sound is clean with absolutely no hiss. You can tailor the sound by easily replacing the socketed OpAmps inside the amp, just make sure you insert them with the proper polarity. OpAmps can range from several to over a hundred dollars for a set. Better OpAMps can give you better depth and a wider sound stage as well as a mellower sound.Remember this is a no frills amplifier with only pair of inputs, it is basically a volume knob and nothing else. But this is perfect when used as a desktop amplifier to drive a pair of desktop speakers. In this mode of operation, you do not need the optional power supply since most desktop speakers are quite efficient and do not need much power.The 48V provides a more heft to the sound with the added power. It can easily deliver enough power to drive most speakers. With either power supply, the amp seems capable of driving even 4-ohm loads without distortion which most modern amps fail to do.Some Pros:* Cheap but great value* Compact size* Very efficient* Swappable OpAmps* High quality components: Elna capacitors, WIMA Output capacitors, Sumida inductors and NCC CapacitorsSome cons:* Fosi used to supply the amp with the copper volume knob as well as the black one but it is now an added option.* The amp goes to sleep rather quickly after the input signal is cut. It takes about six seconds for it to come alive when signal is restored.* There is only one pair of RCA inputs* No Bluetooth capability* No subwoofer output

I had been hearing about the release of this amp from various forums and decided to experiment with it with a couple of speakers that I have acquired I’ve the last 6 years I or so. I’m a bargain hunter at heart.On one end, I have a pair of Klipsch LaScala’s from the early 1980’s that I resurrected from the dead. They were in horrible shape and came from a church that used them as their auditorium PA. They are know for their efficiency and usually have synergies with tube amps. On the other end, I have the electrostatic Martin Logan ESL’s, which sound completely different, are very detailed and have a reputation of being challenging to drive, although the newer Martin Logan’s don’t have this problem as much.I have been using a 90 watt per channel tube integrated amp and was really looking for an amp that was much cleaner and imparted less distortion, which a tube amp for the most part is built to do. The tube amp sounds great but it seems to blur the sound a bit, if that makes sense.With the LaScala’s, the V3 power was way more needed to drive them. It didn’t sound harsh or brittle and in fact, was completely quiet with the volume knob maxed. My tube amp imparts a slight hiss at the tweeter that is audible from my sitting position. The V3, checked all the boxes and did everything well. The highs and mids were nice and balanced and the biggest difference was with the low end. I have 2 SVS SB1000 subs and the V3 really provided nice and controlled texture to the bass region, something that was lacking in my tube amp. I won’t go as far as using the magical language to describe the sound that many audiophiles use but as this is a subjective review, what I can say is that the amp did its job and at this price, it really is a no-brainer for people that even are wanting to use this will quality speakers.Martin Logan ESL’s Challenge: These speakers are known to have dynamic impedance swings, with ohms that often dip, making them a tough act for many amplifiers. But the Fosi V3 didn’t strain at all. It provided consistent power, ensuring the ESL’s remained articulate and expressive. Much better than my tube integrated. The dips in ohms which could cause some amplifiers to falter, only showcased the stability of the V3. Very surprising for the low cost. Again, what can I say…these small inexpensive amps have improved to the point where they are an incredible value.Conclusion: The Fosi Audio V3 isn’t just a budget amplifier. It’s an amplifier that can be used with expensive speakers. For anyone hesitant to use the Fosi in similar use cases, give it a try. For the price, there’s very little to lose.

Very quiet and doesn't get too warm/hot so it's very efficient. It does the job I wanted it to do, power some bookshelf speakers for my computer. I love how small and silent it is and how it doesn't heat up the room when idling the way my full size receiver/amp did.The volume control needs to be over halfway before you get more than a whisper of volume then it starts to act like a volume control above the halfway point - so they have wasted half of the rotation of the volume knob. The preamp out is simply a direct Y connection from the input jacks so it isn't affected by the volume control - this makes it useless for sending to your powered subwoofer as the subwoofer will always be at full volume regardless of where you set the volume on this Fossi amp. In fact the subwoofer will continue at full volume even if you turn the Fossi amp off completely because the preamp out is nothing more than a Y connection to the input jacks.They should have made it an active output tied to the volume control so you could use it to feed an active subwoofer. Even nicer if it had a low pass filter you could set the cutoff frequency.As it is, you would need to put some sort of master controller ahead of this Fossi amp and use that as your master volume control to send to the Fossi and to the subwoofer.