Tube Pre/ Class D Amp - Who has done it?

I have a Shindo preamp into Quicksilver V4 monos(170w into 8 & 4 ohms w/kt150s). Went to a difficult stand speaker, 85 dB, 4 ohm dipping down to 3.2, ouch!  Tried class D power amps because of the drip in impedance, base got faster but everything else, (ie, what I call tube magic) was lost. 
 

Class D has its place in my opinion, just not in a critical listening environment when the life of the music is most important.  

@daytrader bass got faster but everything else, (ie, what I call tube magic) was lost. Class D has its place in my opinion, just not in a critical listening environment when the life of the music is most important.  

+1, yep, and the difference is notable when comparing to good tube amplifier designs and tubes. Getting closer but not there yet [in most cases]. A few designers claim to be as good as or better now with Class-D, and hope they keep working at it. Will be interesting to see more Class-D powering all parts of the main speakers [not just low freq] showing up at the shows next few years, as tbd.  

dehavilland 6SN7 style preamp into hypex amp. Very nice combo but still a bit sterile in mids and bright/forward in highs.

By way of usual audiophile nonsense, I once had my VAC Master tube preamp ($30K) hooked up to a NAD M22 (nCore class D). It sounded great! Much MUCH better than with matching M12 digital preamp, which was comparatively awful. I even considered sticking with this combo for a while (in my second system), or upgrading to the M23 (Eigentakt). However, in the end - yes, I still prefer either a really good SS class AB (Phison) or tube amp (VAC), versus the class D. But that little NAD M22 was a hell of pleasant surprise, and it’s super for the money (my other amps are much more expensive). However, I think it really benefits from a tube pre to round out its sound for best 2ch enjoyment. Yes, it is "drier" in comparison to really good traditional amps. 

For few years i used Primaluna Prologue Premium preamp with Nord Hypex NC500 class-D poweramp. Was quite happy with the result (Focal Electra speakers). When tested RME ADI 2 DAC with integrated preamp instead of Primaluna, sound was clean, but lifeless, unnatural and boring, in lack of better description. Later switched to Primaluna EVO 400 preamp with much lower output impendence, and that had better extension and clarity, very obvious improvements after few seconds of listening!