I got to spend about 5 hours with it, fresh out of the box, using the HD800 out of the headphone output. It's home burning in as we speak. Works fine with a regular US power cable. So this is all subject to change after some burn in.
The sound isn't warm or colored, but there is a definite rumble to the low end. The HD800 has high-quality bass, but often it feels basslight on my other amps. Not here, the bass is fast, clean, extended and kind of stands behind the mix (no mud). The mids and highs are essentially uncolored, the HD800 still has the annoying treble spike, but is fine on lower volumes. The mids are glorious and spacious and I don't sense any coloration whatsoever. I loved it with classical music, especially with with the tipped up bass. I feel comfortable using the DAC out to feed my other headphone amps based on what I've heard so far. It is extremely revealing and powerful. I expect it to pair well with my V200. Soundstage is about what I would expect for a DAC in this pricerange, big and spacious and 3D. Comparable to the Burson Conductor in that regard, for reference (I much prefer the Fostex).
The remote is low quality, but it gets the job done. I don't think I'll be playing with the settings all too much anyway. I feel like the decay is faster/more involving using "Sharp Rolloff", so I'm pretty sure I'll stick with that. The other setting sounded slower. Upsampling at 1X (regular) sounded clean, then the mix seemed to get busier and more cluttered at 2X and 4X. Pretty sure I won't be using 2X or 4X.
For $1500, it's a good deal. $1100 - $1000, it's a no-brainer. I got it for the USB DAC (and the looks, I won't lie) and it's easily my favorite DAC so far, but that headphone amp is extremely good too. Plus I have the option for DSD if they ever release anything in the format that interests me. Only downside is the low quality of the remote.
Last thing is I need to install the latest firmware tonight. Hopefully it doesn't alter the sound. Will update with DAC impressions on my other amps.