Compact ~20WPC Tube Amp

This is way under your budget, but I've been very pleased with the LSA VT-70 from Underwood HiFi. 35 watts/ch with EL34 output tubes (and you can also use 6550 or KT88 tubes in the amp.)  And, besides my good experience, it also has a number of very favorable professional reviews. 

I could stretch to $5k but would prefer to keep it under $4K,

Wish I could find an RM-10 out there somewhere. There are a couple RM-9s which I've had before and love but the heat they put out is just too much!

Quicksilver Horn Monos or Mid Monos

The brilliant Roger Modjeski ( RIP ) designed and built Music Reference RM-10

@dhcod 

Do you have a price range limit ?

Charles

Decware ZMA is a push pull amp that sounds like an SET. 2 yr wait so watch for one on the secondary market. they do show up (I bought one).

Edit to add that there is one listed for sale on the Decware Classifieds forum.

Get a nicely restored Dynaco ST70. Plenty of dynamic power compared to a typical SET amp. Agon member autospec has one for sale here.