I know you want integrated USB, but what I've had success with is a Northstar M192 MKI fed by a Trends UD10 USB-SPDIF converter. I haven't compared it directly to anything, but my gut instinct is that it's exactly what you're looking for- neutral, not tipped up or painful. I've seen used M192 MKI's go for $850, they might drop even more. Finding them is sometimes difficult, though. The Trends goes for ~$100 and would bring the total just under your budget.
That said, the Stello linked above is really tempting. Good luck in your search.