Spectron Musician III - Can anyone comment on it?

With your 1600 lbs E2s I feel you will eventually get 4 pcs MIIIKII or even more with the Bybees and V-Cap upgrades, operating in mono. If you do decide to go that way. In my mind your speakers compell this line of amps.
Mixing up different brands of amp in this type of config will require much more efforts cutting into listening time and you may not be satisfied with the end results, I didn't.
Rex is fitted with true balanced outputs which I am hoping that your active crossover will accept.
''It's a tough call because I've read a lot about the Spectrons being somewhat "rolled off" in the upper register''-- Not at all in my system.

The Spectrons do take some break-in time so when they first come out to the box you may not entirely like what you hear. But after 400-500 hours your will be re-listening to all of your lp's and cd's as if it were the first time.

"I've read a lot about the Spectrons being somewhat "rolled off" in the upper register. . ."

If the above meant that Spectron's treble is not sizzly enough to make your ears bleed uncontrollably, and jarring enough to make your teeth feel like they are being clean with the ultrasound wand by a Sadam Hussein in a bad mood. . . then it is absolutely true.

Else. . . it's just an urban legend; Spectron's treble is open and musical. G.

Spectrons being somewhat "rolled off"

I do agree with you on it, there was some truth in it a few years ago - I heard it on standard Musician III. When they made Signature, I was told, the special attention was given to treble and indeed after I upgraded my M3 to Signature I could hear immense improvement and I thought its one of the best highs I ever heard. May be the best. About the same as Plinius Reference -M - similar signature.

From my conversation with Simon, I understood that in Mk2 they concentrated on the top-to bottom approach and during the process, he said, he noted some schematics which he felt was not needed. John agreed and after they removed it , already fantastic highs became much more open, they bloom, etc

I am cello player and with Mk2 and GOOD (!!!) recordings I close my eyes and I have uncanny feeling that the player(s) is in the room.

As much as I love stereo Mk2, the monoblocks remove additional layers of veil or whatever between me and soundstage. Again Simon explained it by totally removing distortions (don't confuse with random noise) in mono mode and letting music out undistorted.

I know BAT stuff. I agree with you that REX may be the best preamp in the world. I love it! I also know well BAT600SE-M as truly excellent amplifier - however, Spectron is much better. BAT have even order distortions present and you can hear them, particularly during crescendo where no amplifier in the world come even close to Spectron.

I owned or auditioned extensively MBL 90011, Gamut 200 MkIII-M, BAT VK600SE-M, Plinius SA-Reference-M, VTL Siegfrieds and CAT JL1. Sonically, Spectron Mk2 monoblock is simply in another league.

"the name on the faceplate ain't Krell or Mark Levinson!"

If you want noble pedigree then Spectron chief designer John Ulrick is the designer of famous Infinity speakers in the 70's and inventor of the first digital amp. Simply,from 80's he went into pro audio and thus his name has gone from short-term audiophiles memories. However, he has HUGE name among professional designers. He loves music and Simon is (was) professional classical pianist and Yada, Yada, Yada Musician III Mk2 was born

Finally, my friend owned M-L Summits and power requirements were not in the bass region but strangely enough at the top, can't remember why - check your M-L speakers as well.

Whatever you decide - be happy.
All The Best in Your Search
Rafael

I've not heard the Spectrons (mono or stereo) with any of my equipment but at a customer's with Maggie 20.1, the Musician III was incredibly good.

If you need a lot of horsepower, Spectron is worth a listen IMO.