Nicholas at Promitheus assured me that his products would work well with my (at the time) Nuforces. i suspect if the input impedance of your class d was sufficient (class d's tend to be 47k or higher) it would be fine. The Nuforce didn't take much to drive them.
BTW I did introduce a passive into my system (but now with a tubed amp) and it's true what they say...once you go passive it's hard to go back. Transparency and clarity, in short the 'live' experience, is much more. The active pre's I've had couldn't touch this.
