MBL 101 (~1990) - amp suggestions.

Does anybody have experience with those speakers:
Designation was MBL 101, or MBL 101a/b/c (letters may designate colour).
They have _no_ cone drivers, only three 'Radialstrahler' units, the same size units as in later/current MBL 101 range, but lower crossover points. Subwoofers (MBL 201) were optional, I do not have them.
So far I have tried the following amps:
Pass Aleph 4: almost there, but feels like lacking authority. Also, female vocals seem to suffer (males fare better).
300B SET (glasshouse/hificollective): they make sound, even loud if pushed (circuit allows 300B to go A2), yet the match is poor, orchestra becomes a mess.
Moderate power SS AB amp ("INnovative Audio Ultrapath"): pointless. Sounds flat and gutless, worse than Aleph 4 or SET.
Mark Levinson 23: the best match so far. Controlled and effortless; merciless at times (poorer recordings are exposed for what they are).
-- Do you think I can [substantially] improve over ML 23?