My friend had an all-tube Balanced Audio Technology set-up with VK75 amp, playing into some big Tannoys.
I had a similar Balanced Audio set-up but instead of the VK-75 I had VK-1000 SS monoblocs playing into a pair of Sonus Faber Extremas.
I don’t remember either set-up lacking anything in the bass. What the VK-75 lacked in absolute drive it made up for in speaker efficiency. Bass extension was never an issue. We had certain recording; Flight of the Cosmic Hippo or Michel Jonasz’s Le Fabuleuse Histoire de Mr. Swing that would give you that trouser flapping (not the Extremas quite), chest thumping bass and in my opinion, neither amplifier was found lacking in this regard.
Of course with any comment about amplifiers, there has to be a qualifier....’with properly matching speakers”. It really is only sensible to consider the pairing when looking at any amplifier characteristics, because as we all know, there are no amps that match all speakers, but there are some pairings that are absolutely made in heaven.