I purchased a new MA2275 August 2011 with Sonus Faber Cremona-M speakers and the sound was dull and disappointing, I wondered had I made a huge mistake! I waited and waited for the burn-in improvement but it never came by March 2012.
I read about tube rolling on Audiogon and was positive that if I changed the McIntosh Chinese signal tubes I would have hope.
I ordered 12AX7 NOS Telefunken smooth plates from Brent Jessee Recording Supply in Illinois and man what a difference! My Mac is singing unbelievably! All I replaced was the V6 & V7 preamp tubes. I was so stoked that I went further and ordered the very best Telefunken driver tubes ECC801S and I continue to be amazed. This is all I ever wanted.
Of course I am continuing my quest with Brent Jesse for some top of the line Mazda tubes for the phono side.
I suggest everyone with a MA2275 contact Jessee Brent for their tubes. The web site is amateur but has a wealth of information no slick site has, this is the true and real deal here. I'd like to have a beer with this guy sometime.
And by the way, I'm an American working in the Middle East and his tubes arrived safe and sound, no doubt to Lynn's careful packing :-). So where ever in the world you are, rest assure they will arrive intact.
Two thumbs up to the Brent Family Biz. I'm a customer for life.