$3500 to spend on a tube preamp....ideas?

My recommendation is to audition the Audio Horizons. I tried several pres with higher and lower prices and happily bought the Audio Horizons pre totally tricked out. I have no regrets. Hope this helps. Steve

If you can find one the Herron VTSP-3A is a steller line stage. Should work well with the M1's. It would be tough to find one used at your price though.

Save yourself $3,000 and buy a Lightspeed for $500. It has replaced preamps costing several times more than the preamps you are considering. It is amazing regardless of price.

I have the Dude, have heard the VSTP-3A, and had a tricked out Audio Horizons. All three are great preamps and great options. I am very, very happy with my Dude, and have the Herron VTPH-2 phono stage, which is just tremendous.

Honestly, I think you can't go wrong with any of these, but I can tell you that the Dude/Herron combo platter is here to stay in my system.

Lightspeed is made by whom??
For a line stage I love 6SN7s so Cary preamps SLP98 I think you might be able to get a used SLP-05. for very little if you can snatch one before its bought an AE-3 by Cary's subdivision AES. The Signature model with tube rectification should cost you under 1K used. The basic model cost me 350 used and a friend modded it for me.
If you are an octal fan like me then think about Mapletree Audio in Canada. They will custom make the pre of your choice, spec requirements and tube preferences. And The prices are very reasonable. For instance you can decide to use the absolutely best 12SN7s like TS Round Plates because they are easier to find as real NOS and much cheaper than their 6SN7 counterparts. I think the guy's name is Prof. Lloyd Peppard?? No affiliation as usual.