Audible Illusions M3a preamp


AUDIBLE ILLUSIONS M3A PREAMP
Question for any and all M3a owners??? Anyone know the year the last factory "mod/update/upgrade" was done to this unit, so one knows if he has the latest greatest M3a??? Also, mine was purchased as a "factory refurbished unit" & came with the Russian 6H23nEB tubes in 2014, system includes new Aragon 8008( Indy Labs), Linn LP-12, Ittok LVII, Van Den Hul MM-1, Marantz UD8004 Blue ray, & Maggie 1.6's. Question/opinion even if my M3a is the "latest greatest", would the cost of moving to a M3b make my system that much better???  Thank You Kindly
smotojo
As a 24 year AI user, I would say it would be comparable to the difference in stepping up from a 2D to a 3.  This is going by what AI says and what I've read.  I have no actual experience going from a 3A to a 3B.  I've had a 2D and a 3A which I still have.  The 3 to a 3A might have been the biggest difference up to now.
I had a 3A and now have the 3B.  It is night and day difference.  The switching is now done by relays and the noise floor is much lower which makes for a much quieter preamp.
Any ideas of cost trading up to the M3b going direct to Audible Illusions??? Has anyone done this or gone through a dealer??? Any response is greatly appreciated.