So I got my M9 back from the local dealer/service center, no charge obviously, but I was told that there was a charge sent to Mesa.
Set up the M9 in the studio, re-connected the 2 PH 15s and I got 3 seconds of so of my E string, the amp clicked (sounded like a circut breaker) and no volume. Turned it off, tried it again - same thing except that I noticed that one of my PH 15s was silent.
Removed the silent PH 15 and replaced it with a PH 2x10 and then the M9 worked flawlessly and exceeded my expectations for the rest of the practice. The next day I connected the silent PH to another amp and discovered that it now had a blown speaker.
I am certainly no expert, just an average player, so it's easy for me to assume that when the M9 originally cut-out, the "pop" that I heard was the sound of my PH 15 biting the biscuit.
I composed a detailed letter quoting serial numbers of the M9, the blown PH 15, the story behind the repair at the local dealer. The last line of the last paragraph was a simple question. Since in my opinion the M9 took-out the PH 15, is Mesa responsible for a replacement speaker?
That letter was faxed to Mesa customer support on Monday, Nov. 8th and as yet, I've received no reply. I could reluctantly live with the answer that Mesa's not responsible, but what I find disturbing is the 'no answer' at all; that's insulting.