can anyone recommend tube amp for dartzeel preamp?

I would ask Jonathan for his opinion if you have not already yet done so. I cannot respond directly to your question, but note that I have a darTZeel amp and a VAC Renaissance 70/70 Mk. III tube amp that I run with a solid-state, battery-powered Rowland Coherence II preamp. The VAC is a push/pull, 65 watts/channel, zero feedback triode design that autobiases and runs 300B output tubes (it also has a sentry circuit that shuts down any output tube that begins to go outside of safe operating parameters). It is all point-to-point wired, and features very high parts and output transformer quality (ten years ago, the Mk. III retailed for $14K and the Signature version $18K). Mk. III's can be had for between $3K to $4K used. I'm not necessarily advocating this amp - I have no experience running it with Evolution Acoustics speakers - but am simply trying to give you ideas. Again, I would talk to Jonathan if I were you.

Jwm:

The only "current VAC amp" that is point-to-point wired is the Statement 450. I remain skeptical that it is, overall, equal to or better than the Renaissance vintage of amps. It does not appear to be a triode circuit and it is not biased fully Class A. It's also a high-powered design (i.e., loss of transparency and delicacy) that almost certainly uses feedback (disaster), and the output tubes are pentodes. The Kevin Carter-designed Renaissance amps were all-out efforts from the late 90's, when the company was flush with cash from the great economy and its contract to make the Marantz Model 7 /8B /9 reissues. VAC is still a great tube gear manufacturer and it stands behind what it makes, but those days are gone, I'm afraid.

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.

Charles1dad:

I largely agree, and you raise an important point about the practicality of the two designs. The Phi amps may be better suited for the typical 87 db. efficient / 4 ohm speaker. While the Renaissance amps have excellent power supplies and output transformers, allowing them to drive speakers that ostensibly more powerful designs cannot (Lyric in Manhattan could not drive the big Pipe Dreams with the VTL 750 watt/channel Brunhilde, but was able to easily drive it with the 70/70; another Manhattan shop, I can't recall which, hooked up a 30/30 to a pair of B&W 801N's, a speaker that requires bi-amping with big SS amplification, just for laughs, and it drove the speaker), they do have their limits. That said, on the state-of-the-art, 93 db. efficient MM2's with all-darTZeel electronics that the author of this thread is running (my closest hi-fi friend runs MM3's with all darTZeel electronics - these systems play at the very highest level), this gentleman wants the best sounding tube amp he can find, i.e., full Class A biased, directly heated triode, zero-feedback, point-to-point wired and otherwise featuring top parts and build quality, etc. He also writes that he wants auto-biasing, something that puts out 50-75 watts/channel, and that he can buy used $3,000. A 70/70 Mk. III fits this profile.