Tannoy Westminster amp matching question.

Wow, 600 ohms input -- what were they thinking?? Sometimes it's hard to tell whether such a wacky spec is real, or a result of "lost in translation". Based on your experiences, sounds like this one is real.

Preamps that will handle 600 ohms are very rare. I have no experience with Atmasphere's products, but from all indications I've seen, they'd be an excellent choice. Another route (as you learned with your Lyr) is to look for headphone amps with preamp functionality. I'd look for something tubed that doesn't use electrolytic output caps -- which are the typical way that cheap tube headphone amps handle the low impedance loads. I used to have original Eddie Current Zana Deux; it served very nicely as a preamp and had an output impedance of only 16 ohms (no remote, though).

To be honest though, it doesn't make much sense to go down a route you wouldn't otherwise, just for amps that are WAY off the beaten path. The Atmasphere may be a good option because it'll serve as a top flight preamp whether you stick with these amps or not.

I’m still driving my Tannoy Canterbury with 275 Watts/ch push-pull tube power (Rogue Apollo Dark monoblocks), and have absolutely no regrets! Amazing sound; highly dynamic and "live" sounding, while perfectly maintaining a neutral/natural balance across the spectrum. It has touches of warmth/sweetness just where it’s needed, without drawing attention to itself. I recently upgraded from Canterbury SE to GR, and that was a huge improvement across the board. I would’ve gone for the Westminster GR too, if I had the room.

And I can be content that 275 Watts here is already way more than ample for this application, and I don't need to entertain silly upgrade ideas of bi-amping, bridging (2 upgraded Zeus amps), etc. 

Certainly, there will be other great options, especially with the extra efficiency of the Westies. But I’m very happy with my arrangement!