I just bought one of these units off eBay, and I'm very impressed with it.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=310-316

It's main purpose is to act as a USB DAC (essentially an external soundcard) to let you plug in regular stereo speakers. You can also use it as a headphone amp and the quality is very good considering the cheap price of the unit (cost me roughly NZ$190 landed).

If you tell it to do so, it'll automatically turn itself off and on when the PC its attached to turns off/on, and it'll fade the volume back in just in case you left it turned all the way up.

It's only a 15Watt unit, so don't expect to power big speakers at great volume, but it runs my Energy bookshelf speakers at a decent high volume at around 2/3 of the "dial".

I've been after something that performed the exact function of this unit for a while (small low power amp that will run regular speakers and headphones) and the fact it acts as a USB DAC instead of just having RCA inputs was a bonus.

I already popped the lid off it, and the circuit quality does look to be as clean as it is in the pictures which is nice.

Very pleased with the purchase.

I almost bought the Maverick Audio Tube Magic D2 and A1 combo, but that would've been utter overkill and 3 times the price. Marvellous units though.