@kennycÂ
+1 @lak, ​​@charles1dad is a knowledgeable owner/user of the Coincident Frankenstein MkII. IIRC @charles1dad did not like the upgrade to MkIII, but I’m debating to get mine upgraded to mkIV.
Hi Kenny
I believe that you'll be quite pleased with your Frankenstein and Vollti pairing. I can't think of a single reason as to why this should not be a marvelous combination. I do need to clarify something however, I have not had the opportunity to hear the MK III or IV Frankenstein models (Nor the new stereo version). So I'm can't offer any opinion of them.
I can't imagine either of the mono block models taking a step backwards from my MK II mono blocks. Coincident does not do model upgrades that frequently. When they do it's usually For a good reason and subsequently an improvement.
As I have stated in the past, I have owned my MK II since bought new in August 2009. Upon the very 1st listening session I knew I had made the right choice.14 years later and if anything I appreciate This amplifier even more so. It is a fabulous 300b SET.
As far as speakers are concerned reasonably high sensitivity is desirable. Equally if not more important is the speaker impedance characteristics. Higher is generally more advantageous along with a simpler crossover design. I'd seek out speakers that are designed with the intention of usage with SET amplifiers.