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

In some cases I believe this is to allow for the OEM to produce their own high impedance input stage.  If you make pr eamps, maybe worth taking a gander at incorporating your own front-end. :) 
 

Thats what we have done with our Hybrids. 

That’s what we have done with our Hybrid amplifiers. One uses a DHT input stage. I didn’t want to go to far into that as didn’t want the post to look like a promo. 

@erik_squires 

The seemingly consistent feature among previous generations of Class D amps has been relatively low input impedance. 

FWIW the input impedance of our class D amps is 100K single-ended or balanced. Anything can drive them.

So - I’ve been (re)assembling my cabin system. It now consists of the Atmasphere MP-1 mk 3.3 preamp (tube) and Atmasphere Class D monos and I’m pleased to say it’s a very good combination. It’s different than my primary system which is solid state preamp going into a class A/B amp but they’re both very satisfying even though they bring different things to the table. 

I’ve had class D amps before (PS Audio Stellar S300, NAD M22, NAD M33) but they all failed to fully satisfy. They weren’t bad, but they also weren’t that great and I’ve since sold them. The Atmasphere Class Ds are notably more musical and a terrific value. I will say they’re not quite as good as my Class A/B amp to which i directly compared them. But they were also a LOT less expensive. 

So, my recent experience is a tube preamp/class D combo is a nice pairing.