Did I fry my output transformer?

[theculprit]

What up dudes, bad day to be an amp

About a year ago, I bought a Randall RG100ES. While testing it, I accidentally connected the speaker output of the Randall to the speaker output of my Peavey Triple X. Although the Triple X was off at the time, I assume it still took the load, especially since I had the Randall cranked to max volume. It never occurred to me at the time that I may have damaged the amp so I never turned it on to check.

Fast forward to now, after not using the Triple X for almost a year, its volume is very low almost none existent, and the tone is thin and lacking gain. I did the "tap test" on the tubes and found that one of the preamp tubes was coming through the speaker. Thinking I may have damaged the preamp tubes, I replaced all of them with a new set. Unfortunately, the amp is still in the same state and the preamp tubes did not make much difference.

I thought it may be the power tubes but I spoke with a local amp tech and he thinks it is the "damper diodes" that took the hit in the Triple X. Unfortunately, he's out of town and won't be back for another week.

I plugged my guitar into the return loop to see if I could get a signal in the power section but I got a loud screech kind of like feedback so I shut it down and tried again the next day. This time I wasn't getting anything out of the return and when I switched to the clean channel I heard a pop. I tried to see if I could replicate it but it didn't happen again.

Any thoughts on what it could be?