I would strongly recommend hearing any amp first before buying. In particular, putting money down for something you have to wait three years for seems very risky. I've heard three Decware amps and all of them were whimpy sounding things that sounded pleasant, but, very limp and unable to deliver punch. The speakers they were used with were high efficiency speakers (about as easy or easier to drive than the Volti Razz).
With low heat a big priority, Class D solid state makes sense. Find a high quality lower powered Class D amp.
If you are sticking with tubes, the advice above about Audio Note Oto or Soro is good, if you can find something used in your price range. I would not be looking at hot running tube amps such a those employing KT88, KT120, KT150 or KT170. If you have someone to service your amp, you might be able to find something vintage that runs EL84, 6L6 or KT66, and even EL34 (not one of my favorite tube types, but some amps running those tubes sound good). These tube types I've mentioned tend, to my taste, to sound better than the KT88s you run (not as hard or brittle sounding).
Good luck in your search.