Amplifier upgrade advice under $2000

Hi!  I have a new pair of speakers on order and want to upgrade my power amplifier to be ready when they arrive.  My current system is Klipsch Heresy III, Onkyo M504 amp, MiniDSP SHD preamp/streamer/room correction, and SVS SB12 sub.

Scheduled to arrive in December are Ohm Walsh 2000.  Research indicates these like a lot of power.  If the Ohms don’t work out I’ll shop for a used B&W 804, so still probably needs good power.

So, with a budget under $2000, wondering if I can get something that sounds significantly better than the Onkyo.  Used is fine.  Brands I have seen come up in the price range are Classe (ca-150), Vincent (331MK), Krell, PS Audio, Parasound, Bryston, etc.

I want to know if this would be a significant upgrade in this price range.  My sense is that brands like Rotel, Adcom, Emotiva, etc. would probably not change the sound all that much.  I also have a Crown ps-400, for example, that sounds pretty much identical to the Onkyo.

I recently tried out a Rogue Atlas Magnum tube amp.  It sounded great with the Heresys, a definite upgrade. Unfortunately  it created a loud speaker hum that I was unable to fix.  But it did make me crave the tube sound.  But it seems like finding a high powered tube amp to work with the Ohm Walsh is going to be challenging.

Sorry for the rambling, basically, is it worth spending $1-2K on a new amp or should I wait until I can get into a higher price range before ditching the Onkyo (which has those awesome green meters!).  Thanks!