Class A Solid State Sound

I have not heard the amps you mention but I do generally seem to prefer amplifiers that use Bi-Polar output devices, such as Clayton's M300 monos.  One possibly meaningful comparison I have made was when I owned both the M300s and Lamm's M1.2 Reference amplifiers for an extended period of time (i.e., months).  I ended up keeping the Claytons and selling the Lamms but I cannot rule out that my preference may have been due to the difference in power between those amplifiers. 

@auxinput 
Your description is pretty much what I hear between MOSFET and bipolar or BJT output stages.  BAT solid state amplifiers are another that to me have that soft/warm/fuzzy sound.  The effect is less noticeable in the Lamm hybrid amplifiers I have owned, but still perceptible as a fuller, less distinct and slightly boomy bass presentation, at least to my ears.

How about PS Audio's BHK  Signature 300 with a tubed input stage and MOSFET output stage using exclusively n-channel devices for both the positive and negative signals.  Claimed power output is 300/600/1000 wpc into 8/4/2 ohms and according to JA's measurements those specs are mostly confirmed with 370/620/950W into 8/4/2 ohms, although like many manufacturers, it appears they sort of fudge the 8 ohm power rating (lower than actual) so they can claim that the amp " doubles the output current with half the impedance."

I appreciate that they provide a power rating at 2 ohms but cannot help wondering the reasons for JA's comment that the amp "was less comfortable at lower powers into this low an impedance" (i.e., a 2 ohm load), and Fremer's comment that, "there's still more weight, power, and physicality to be had in the very lowest octaves."  Curious why an amplifier that provides 950 wpc into 2 ohms would be anything less than a powerhouse into low octaves.  Does the MOSFET output stage have something to do with it or, how about the dual differential design?

JA - "The output impedance (including the series resistance of 10' of speaker cable) was on the high side for a solid-state amplifier, at 0.16 ohm at all audio frequencies."

Upgraded and former power supplies in my Class A monoblocks.....

https://www.usaudiomart.com/details/649314340-clayton-audio-m300-class-a-monoblock-amplifiers-custom/images/1380838/