I've got an iBasso D10 Cobra portable digital-to-analogue (DAC) Amplifier combination for sale that I've been using for about four years now. I originally bought this from the webstore and imported it to Korea for about $350 back then. It's a great device that I have used both as a portable dac/amp (plugged directly into the old 30-pin connector on my iPods) and later as a desktop DAC, providing a clean signal from my Mac's optical (toslink) out to my tube amplifier (also for sale, see my other ads).

As it is not the youngest of devices, I'm sure the battery isn't as strong as it once was. The last time I ran it off of its battery a few weeks ago, it lasted about half a day I believe (of continuous use), but that's still quite good. You can run it while it's charging too, it charges via its USB port.

There's quite a few input options on this one; 3.5mm line-in, Coax, USB and Toslink. Output is either amplified via the 3.5mm headphone jack or unpowered via the line-out jack.

For more information, you can check out the official iBasso page of the (now-discontinued) product here:

http://www.ibasso.com/products-detail.php?id=94

If you have any other questions, feel free to contact me.