Vivid Technologies V1 portable amp/DAC

http://www.head-fi.org/forum/thread/484033/review-vivid-technologies-v1-usb-dac-portable-amp
 
That's my in depth review. In summary:
 
The Vivid V1 is a deceptively powerful little amp. It performs pretty well with almost any headphones, including full sized and IEMs. It has a somewhat unique forward and fairly aggressive sound signature, which is surprisingly pleasing. It pairs especially well with the Sennheiser HD600. The battery lasts a long time, and the USB DAC function is handy; it isn't exactly a top notch DAC but is almost certainly better than the one in your laptop.
 
Several people besides me have made positive comments about this amp, and for the price I think it is great entry level product.