can anyone recommend tube amp for dartzeel preamp?

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.

Radioheadokplayer,
It sounds like you have some listening to do. Many of the recommendations provided have interesting and worthwhile, but they will provide you with different versions of tube-ness.

I have run both solid state pre and tube pre with tube amps for a while. Currently, what spends the most time hooked up is a vintage solid state phono/pre with tube amps. If anything, I may change my amps - not sure if I will go tube or solid state. Having heard my Audio tekne push-pull amps on my main system, I know I am missing something in the 'sweetness'/'lushness' category but I also need more power. May end up bi-amping to get the power on the bass.

In the preamp spot, I can recommend the Jadis JP-80. They are not the last word in detail and transparency but it is a wonderful-sounding tube preamp. Arthur Salvatore at high-endaudio.com has some interesting modification suggestions to improve an already good pre. I have not tried to implement them yet.

Personally, the tube amplification equipment I would most like to try is the Atmasphere line-up. If your speakers do not present an ugly impedance load, you might be able to make the amps work. You might also be able to make the amps work through an auto-former.