Pros: Outstanding 24/96 USB section, sleek form factor, great price to performance, clear and detailed sound signature, fast, synergy with Sennheiser HDs
Cons: Might not go well with bright cans
I purchased the Nuforce Icon HDP along with Sennheiser HD 650 headphones as my first desktop setup about six months ago. I'll start off by saying that the HDP has been a fantastic purchase that I am thrilled with and enthusiastically recommend, especially as a starter desktop setup.
The HDP has loads of power and easily drives my Sennheiser HD 650s and other high impedence headphones such as AKG 701 with lots of headroom to spare. This is an awesome attribute for a unit at this price point as it will have ample power for almost any headphone on the market, regardless of price. With my Sennheiser HD 650, I usually listen from 11 am to 1 pm on the dial and never go past 2 pm. It absolutely drives them authority and tons of power to spare.
The HDP offers a sound signature that is very clear, transparent, detailed, fast, neutral, and with a nice sense of overall polish and refinement to the sound. My previous Dac/amp prior to HDP was the very popular portable Ibasso D10. The HDP was a very significant improvement over the D10 in all areas. The HDP seems to pair especially well with headphones that are bass heavy and not bright, such as the Sennheiser HD series and Denon AHD series. It specifically does a great job of really tightening up the bass on these headphones, which can be a little boomy or loose on many other amps. With the Sennheiser HDs especially, it also helps give them that extra detail and speed they can oftentimes be missing. The HDP is also a really nice combo for the AKG 701/702 as it really gives them extra bass weight.
One area that was a huge bonus for the HDP compared to other popular units in its price range is the fact that is has an outstanding USB section that supports full 24/96 high resolution music files. I regularly download high resolution albums from HDTracks and play them over my laptop via USB and they are very noticeably better than standard 16/44 regular cds. I have tried comparing the HDPs USB section with its coaxial and optical inputs on numerous occasions and have never been able to discern any differences, which is high praise for the quality of its USB section.
Since having purchased my HDP, I have attended several local meets and have auditioned gear much more expensive than it such as Woo Audio WA6, Beta 22, Bijou, Eddie Current ZDT, Supra, etc. While the really high-end gear does exceed the HDP--most noticeably with larger soundstage--the price to performance ratio of the HDP compared to any of these more expensive units is just phenominal. No matter how high-end of gear I audition, I am never disappointed going back to my HDP. My HDP has helped me to content with my gear and focus on my music collection. While I will likely upgrade to higher end gear over time, I am truly enjoying my HDP in the meantime and am in no rush to upgrade any time soon.