Oops! -
I didn't read the previous post carefully and didn't have time to write much detail as I was rushing out of the house for an appointment.
The lp which didn't impress me was the "K622" (Clarinet Concerto) produced (and hyped) by John Atkinson of Stereophile. I have not heard the K581, so can't say anything about that one.
My experience with K622 is the Vinyl, which was mastered from a discrete tape recording of the same performance, so possibly the SACD is better sonically - though I doubt it. My main beef is with the performance(s) anyway. I pretty much came to the opinion that Michaelson is a very good amateur player who happens to own Musical Fidelity, and has the resources to issue, and the industry friends to promote, his own vanity recordings. The playing is relatively faultless, but not of the interpretive level of a Stoltzman, Meyer, Drucker, Kell, Wlach, etc. There are HUNDREDS of working, real PROFESSIONAL clarinetists playing worldwide, and there's a reason only a handful have recording contracts - it ain't that easy to rise to the highest artistic levels (and/or they're not biggies in the Audio Industry).
Overly conservative conducting probably played a large part, too. The whole thing was so flat - I tried a number of times to change my attitude (since it's a nice package and I really wanted to justify keeping it), but I was not once able to listen through the whole disc due to boredom. I just saw no reason to keep this lp.
Anyway, that's my opinion on K622 - Since Audphile1 is a clarinet player himself, it would be interesting to hear his take if he has heard any of the Michaelson issues.