can anyone recommend tube amp for dartzeel preamp?

If you want a real tubey, syrupy sound, I'd look into a used Cary V12R. They're 50 watts triode or 100 watts ultralinear. You should be able to pick up the V12R at under $2500. The CAD-120 mKII may also be worth a look, but I have no experience with it. I can't comment on how nice the V12R play with your other gear though.

Don't agree with you. Kevin will tell you his latest amps including the 300.1 sound better than the vintage 300B. The 300.1 does have a triode switch. Class A does not necessarily make it a better amp.

Vac poweramp (vac phi200) would be one of my candidates to mate with your dartz pre-amp.

My recommendation is the SAS Audio Labs Ultralinear 50 watt monobloc amps. They list for $3500 and are autobias. Steve is a gifted designer and these amps along with his 11A preamp are stellar. His products are also known to work well with other gear both solid state and tube. I haven’t heard the dartzeel, but I am aware of its reputation. I have heard other very high end solid state and tube gear, and to my ears the SAS will go toe to toe with the best of it. I therefore believe the SAS amps would sound fabulous with the dartzeel preamp and give you that slight alteration of flavor you are looking for. Another plus is that SAS has a 30 day money back guarantee, so, if the sound is not what you envisioned you can return them and try something else.

Jwm: Kevin Hayes is a good guy, but he's a businessman and is not going to say that his current production gear is inferior to his past gear ("Yeah, gee, we don't make'em like we used to"). I know two VAC dealers, however, who can speak to the change in his business model and how his recent production stacks up against the Kevin Carter-era Renaissance amps - according to them, the Phi amps are not in the same class as the Renaissance amps, which makes sense given the Phi amps' cheap circuit boards and pentodes. In addition, an acquaintance of mine had both a Phi amp and the 30/70 Signature monoblocks for long periods in his system, and he found the 30/70's to be the better amps by a good margin. As for the Statement 450 amp, VAC went back to expensive point-to-point wiring, but that amp will have the issues listed in my previous post.