After reading the diyaudio forum thread I ordered some of these low cost units to play with. So far I have been pleasantly surprised how good it is, and how little electricity it uses.
The first unit I got (pre-assembled) I blew up trying to feed it 20VDC.. so lesson learnt, I ordered two more in kit form from the same ebay supplier.
It has replaced a 50W Hifimediy T2 tripath amp in the HF section of my active speakers (crossing over at 600hz) so the lack of power is not an issue. As the speakers are quite high sensitivity, 103dB even with 7db of LPAD added, the background noise is. The amp is a bit noisier than the T2 amp, but still not audible away from the waveguides.
There was a bit of messing about with power supplies – it’s quiet running on a 12V battery – but I dont want to keep having to charge the battery etc. A number of assorted 12VDC power supplies on hand caused a fair bit of increased noise when used with this amp, even though quiet with other amps.
Eventually a 20VDC SMPS (reasonable quality unit) used with an low cost LM317 regulator module was found to run this amp sufficently quietly.
I’ve purchased two of the kits, and built one with the stock parts, and one with some upgraded capacitors from Rockby. Both boards have the volume pot and 3.5mm input removed, with the RCA sockets wired directly to where the volume control would go.
It’s hard to say, but is easily as good or better for the purpose I’m using it for than the 50W tripath.
Also it only uses 1.9 – 2.0 W idle and barely more than that at moderate volumes, that’s actually less power than the Class D/T amps I’ve measured.
Enclosure is a 60c plastic tray from the discount shop – the slots on the side have made these handy for quick prototyping enclosures as it’s easy to mount RCA and banana plug sockets, or cut out a larger hole for power – plus the slots provide ventilation.