Tube pre for class d recommendations

I second or third the Schiit Freya recommendation, but you'll need to swap out the stock tubes. I'm using new production Electro-Harmonix 6SN7 with very pleasing results not only with a pair of Ghent Audio mono blocks but also in front of a newly acquired Carver 275. It's versatile and the price is right.      

I have a Rogue Hydra which is a hybrid Class D and have had it paired with three preamps for extended periods of time and was very happy with all three.  Ayre K-5xeMP, PS Audio BHK and Art Audio Composer.  The latter two are tube units.  I also tried and demo'd 4 other preamps through time.  All solid state which I hated.  

The brightness that still lingers in most Class Ds can absolutely be offset by a tube pre.  I found the stock tubes on the PS Audio to leave a bit of brightness but rolling in a pair of Tunsgram's did wonders.  The stock tubes on the Composer are amazing and will temper that brightness beautifully.  Full disclosure, I am the importer for Art Audio.  

I offer a 30 day no questions asked return policy.  If you don't like it, return it and you only need to pay shipping back to CT.

I believe Rogue has been doing tube pre and Class D power for some time now.

Interesting Ralph.
I have 2 foundation research LC2...one grounded and the other lifted ...done by Ed....that I used. Meaning, I was really giving it the old college try to make it work.

Lifting grounds is not going to do it with the UV-1 since its really hard to ground loop it through the power cord.

We did run into a hum problem with a dealer of ours that was using a Topping amp which is class D. The amp was only $80.00 on Amazon so I bought one but could not duplicate the complaint with his UV-1 or any that we had here in the shop. My best guess is that there was something wrong with his amp but its all water under the bridge so I don't think we'll ever know. Otherwise we've been able to solve all the hum problems we've encountered with the UV-1 except for that one. The dealer sold that preamp and the customer seems to like it a lot.

The UV-1 has an aluminum chassis and a steel bottom cover. It can hum if placed near a power transformer or the like since aluminum does not shield at audio frequencies.

My Freya (now the "vintage" version as it has a hotter output tube section which, alas, the newer versions have tamed somewhat) sounded quiet with the supplied "mystery" tubes, but they were boring so I moved on to new Tung Sols that look great! Also boring...so...NOS Sylvania "chrome domes" and RCAs have been doing the job real well and I’m not bored with them. My power amp is a single ended Had Firebottle HO (yes, a HO...says so right there) with a 6SN7GTB (NOS alleged Amperex) driver tube and I only mention that to point out the synergy of tube types, which means nothing. What does mean something is the fact that tubes are more fun than Class D will ever be...tubes can be looked at, burn yer fingers, and swapped out willy nilly. Class D can stay in my little Ampeg "Porta Flex" bass amp, flying above your head in phased array PA speakers, and in the future perhaps a better toaster, but not in my hifi or guitar amps...no no no. Less heat, efficient power...boring.