@sim_audio_nerd
I own Coincident SVII speakers and still own the Frankenstein monos. However, I found that the Franks just didn't really have the guts to do justice to the SV's. My room is about 14' x 20' x 8' and I do listen to a fair amount of orchestral music. In contrast to the experience of others above, I found the Atma-sphere M-60's to be a much better match for this speaker than the Frankensteins in my room with my music. My M-60's have the V-Cap upgrade, the M-1 power supply, and have enjoyed the benefit of careful 6SN7 tube selection. Also relevant is my use of the Coincident CSL with Psvane WE replica 101Ds. The later coupled with the Atma-sphere amp provides a very nice measure of SET magic in my system without the downside associated with driving low efficiency (yes, 92 dB for an SET amp is low efficiency) speakers.
As I said, I still own the Franks and on very rare occasions rotate them into the system for a day or two, but they don't stay longer than that. If I were using speakers having an efficiency in the mid to high 90's, it might be a tougher choice. The Franks really are wonderful amps when equipped with top notch tubes.
I have no experience with Pass amps and won't speculate on how they might compare with the Franks in your set up. But I will say that if you are buying a new amp for your speakers, I just don't think that the Franks will be the best choice.
I have found my SVII's to be wonderful speakers, but their performance is perhaps more system dependent than some other speakers. The SVIII's appear to be a very similar design using better or newer crossover and drivers.