OP, the sky’s the limit. These are merely stepping stones:
https://www.usaudiomart.com/details/650169340-jeff-rowland-925-mono-amplifiers-55-off/
https://www.audiogon.com/listings/lisbh56g-aries-cerat-essentia-tube
https://www.usaudiomart.com/details/650302654-atma-sphere-class-d-mono-amplifiers/ (these are already sold)
it’s a fun part of this hobby. Frequently enough one gets to be like Miranda seeing something new & special, although common to others, for the first time.

