Yesterday I A/B'd it against the on-board sound in my (mid-2004 vintage) Compaq Evo PC at work. Wow, wow, wow! The on-board sound is not bad, but the teensy Turtle Beach unit absolutely spanks it. The lows go very deep and solid, the highs are good, and the mids have clarity and presence far beyond what I heard from the on-board sound. "It sounds like she's right next to me," commented the friend I had listen in on some jazz vocals.
I highly recommend this device to anyone looking for a no-fuss way to improve on the sound of their desktop or laptop PC on a budget. Again, this is just a $30 unit at list price, sold for something like $24 at NewEgg and other discounters, and it comes with nifty virtual-3D drivers and optical-out besides. You really get a lot for the money, and it's a lot less trouble than installing and configuring the similarly-priced ChainTech internal board. (I haven't A/B'd this against my ChainTech at home, but might get around to that this weekend if anybody indicates interest in the result.)
I tried it both amped and unamped. The sound was a big improvement over this PC's built-in either way, but for best quality I definitely recommend amping it (sounded great with my "work amp," a current-model Headsave Home-Vibe, 8620/24V).