Rich; organic true balanced amp w good detail $6k

Suggestions welcomed & appreciated- here are the Criteria:

- fully balanced architecture
- rich, organic sound, extended bass, silky highs, but not at the expense of obscuring detail
- No OTL (too many tubes/heat)
- SS (Class A bias) or tubes OK
- 20-200 wpc ok, the lower the better though all things being equal- well built power supply crucial
- stereo amp easier to put on my Sistrum rack, but mono-bock architecture also considered if better performance
- $6k or less used would be ideal, but would consider up to $8k used if there are no world-beating contenders at the $5k-$6k used price point

Preamp is a modded Sonic Frontiers Line 3- extremely neutral, hence the desire for a richer-sounding amp to balance. High efficiency speakers from Coincident- large open concept room (main floor of house). Re: tubes, have used ARC VT-100 MKIII- good- airy w big soundstage, but meatier mids would be better. Also had Wyetech Topaz 20-watt SET, superb, if slightly lean in the mids (and not fully balanced, but shows you how powerful 20 watts can sound with a well-built power supply) For SS, am considering Pass XA.5 series (they now can run balanced from what I understand?); Clayton Audio M-200 (but unfortunately over the price-range).

Thanks in advance for any suggestions- I have an open mind, so bring it on!