Hi There,
I own a stiletto ace combo, which I bought from a board member here a few weeks ago. I had some problems, some similar to yours - I own an original Mark I and a Mark IVb and as soon as I got the amp I jammed with a friend who plays way too loud, it seemed that the volume on the stilleto was weak so I replaced the power tubes with a new set and still sounded weak - ok, I pull head from chassis to check out all the tubes and notice that one of the black screen grid (?) resistors on the power tubes is disconnected at one end. Called Boogie Store, they told me sometimes when a tube redplates it will get so hot it melts the solder on the resistor, so I went down there with the chassis only, John soldered the resistor back on and told me one of the power tubes was bad, I had bought them at the boogie store (didnt have reciept with me) so he put a new set in gratis. He also told me I should transfer the warranty on this amp asap (ie I bought it from a third party and it was not yet under waranty).
Ok so I go home, mount the chassis in the shell and fire it up to see if it is fixed - the amp is louder, runs great for 5 mins and starts to sound scratchy again - I decide to crank the input and then the master vols to see where this is coming from, when I crank both to 10 after about three seconds the volume drops to about 1 watt as you describe. **** - ok, take the chassis out again and I take a look - BOTH screen grid resistors are now disconnected at one end, the end that hooks to the tube socket. Call Boogie store and they say, call factory and transfer warranty, then bring it in - oh also take out any non boogie tubes before I bring it as they void the warranty. Next available time (monday following) I called factory, transfered warranty, replaced all the preamp tubes with new boogie 12ax7's (v1 with the mesa spax7a) and take amp back to boogie store, John says gimme a couple of days.
Two days later he had it fixed, I had requested they test it cranked - everything seems ok. The new power tubes he had put in were still good. I guess part of this problem is this: The head and the combo both share the same amp chassis, boards etc, but in the combo the amp chassis is turned upside down. This means that components that are inserted into the top of a circuit board are now hanging from it when the amp is mounted in combo. So when the tubes get really hot the solder in the hole for the grid resistor could melt and the resistor fall out, at the hot end anyway. John mounted the resistors on the opposite side of the circuit board to prevent this. Since getting it back it seems to be fine, no further problems - however I have not cranked both vols to 10 again and I am not sure I want to. My observation is that this combo is (duh obviously) not as loud as either of my Mark's, and I miss the headroom. I recently picked up a Simul 295 and on my last trip to the Boogie Store I got a pair of 1x12 EV Theil cabs they had on consignment ($500 for the pair) so I am gonna do the w-d-w thing to get the volume up, I wanted to do this with my Mark IV anyway so I will see how it works with the stilleto also. I am very interested in how the deuce II you bought sounds, I considered this but have no space for 4x12 cabs.
I would say that I have found the Boogie Store people to be extremely helpful. I mean come on - fixing something I bought used, that the warranty has not been transferred on, for free, the minute I walked in - where can you get this kind of service? Granted, it is a mesa product and should not be having these issues in the first place (resistors falling out of chassis wtf??) but that would be design issues and given the situation John has been extremely helpful.
Additionally I would note that the spax7a reduced internal feedback (microphonics) significantly. There was in this previously 2 x tungsol, one gt12a7-c and 2 x mesa 12ax7.
