I have repeatedly read comments in forums that you generally give up something in bass tightness, definition and impact when a tube amp is used as compared to a SS amp.
Undoubtedly, these people are not doing EVERYTHING ELSE right, or that would not be their experience - trust me! And by the way, are we talking about their experience(s) strictly with CLS's; or with hybrid electrostats?
Tube amps put out a tight accurate bass signal, the same as any SS amp. What tube amps CANNOT do (very well, because of their damping limitations) is they cannot exercise tight control over big, sealed air-suspension cone woofers! However electrostats are quite easy to control, even the bass, even with tube amps, because their diaphragms are very light weight, AND they don't produce a reactive signal like electrodynamic (cone) speakers do.
You seem to be beating around the bush while trying to avoid putting my suggestions to the test -- and did you not own a pair of my favorite speakers, I wouldn't take the time to try and convince you ;-) So before you decide you don't agree with me, why don't you try implementing all the tips I gave you? I think you'll be quite pleasantly surprised:
>Speaker cables (low capacitance and under 8 feet)
>One sub, between the panels. 90 phase angle, 35Hz crossover, lowest possible volume.
>Oh, and make sure whatever preamp you're using has a low enough output impedance to drive a tube amp easily. It should be a tenth (or less) of the (tube) amp's input impedance, or you will get high and low frequency rolloff.