Suggestion used tube amp between $1,500-2,000

Honestly, in your price range I think you would be better served getting a tubed integrated amp. Look for a used PrimaLuna DiaLogue Premium HP, or Cary SLI-80. With your speakers I think you would probably need the 80 wpc in Ultralinear, but if your room is small enough, maybe you could use the triode mode,

I’ve owned the ARC LS-7, and it’s not a very good preamp to be honest.
Integrated amps get a bad rap sometimes, but they really do give you more bang for the buck in your price range and even much higher.
I’m currently running a VAC Sigma 160i integrated amp, which lists for $10K, and handily beat the $20K of separates that I replaced with it.
Not only is an integrated amp more bang for the buck, but it’s one less power cord and pair of interconnects to buy too.
Personally, I wouldn't head into the separates market unless I was looking to spend over $30K.

Cheers,
John

Well the ARC and Cary sound are very different. Both have their fans, but only you can decide whether you want the transparency of the ARC or the warmth of the Cary.