I have a stereo in my garage that I use to listen to while I work out there (two older JBL loudspeakers and an old Radio Shack subwoofer). The center of that system was an old iPhone feeding tunes into a traditional big heavy black Yamaha receiver via the iPhone's headphone jack and the receiver's AUX input. But I got tired of that big receiver taking up all that space.
I came across this Fosi amplifier, and it looked promising. Ten minutes after it arrived it was set up and powering my system. I love that this tiny unit also has a sub control, since the sub iteself is a bit inaccessible and it's not easy to get to the sub volume control.
To my ear, and at the volumes I use on that system, the sound quality from this Fosi amp is excellent. And I love the space it saves.
In fact, I liked it so much I bought a second Fosi amplifier. I'm using that one with my desktop computer system, taking the computer's audio out and adding two Infinity bookshelf speakers I bought at a garage sale. It sounds so much better than the "computer speaker system" it replaced.