I am using an Zesto Andros 1.2. It is attractive, flexible and sounds great (of course).
George is one of the nicest guys in the industry, and returns calls himself.
Finally, I am using the stock JJ83ECC 12AX7 tubes, which are inexpensive and George said sounded better than everything else, including NOS.
If I were upgrading, I would look no further than ARC or Zesto - two of the best at your price point.
Borrow/demo a short list (maybe top 2 or 3) to make your final decision.
I am not affiliated...