Is a VTL ST-150 enough?

The V.A. PARSIFAL need a amp with quality watts (balls) to get out the tremendous bass they are capable of ....
You should go at least to the MB-450's if you want to stick with MBL
For the summun you could match NAGRA amp or LAMM HYBRID amp
just a suggestion ...

I'm a VTL ST150 user (disclaimer: I'm also a VTL dealer) and I can only have high praise for it. You should notice if the power is not enough, especially on how it control the low frequency. I've tried briefly the Triode option but I've preferred the Tetrode mode that, at least in my system, offer the best performance. I've also used the Nordost Frey as a complete cable loom (now I'm using TYR, and BTW, I'm a Nordost dealer too)and IMHO they matches very well.
I think too that VTL should have another stereo amp in between the ST150 and MB 185.

David Manley made his amps switchable to triode because, given a reasonable load, he thought they served the music better. If speakers sound better in tetrode than triode, I suggest that they would sound still better with a good solid state amplifier - like a CJ 2500A.
Speakers and amplifiers are literally made for each other. Most modern speaker designs are made assuming high current solid state amplifiers. High voltage devices like tubes do best when given loads that do not require gobs of current and steep filter curves. Electrostatics, on the other hand, are tough on solid state designs and, as they are high voltage devices, they were made for tubes.

High voltage devices? Do really know what u are. Talking about? seriously read transformer theory before you make statements like that! Tube need an output transformer so they can reduce the output voltage! Therefore, voltage in high voltage out low but current high to speaker just the same as conventional transistors.