My beloved Sugden Musicmaster appears to be fried - to the best of my knowledge this is a SE class A design, but I wouldn't pretend to know anything else about the circuit topology

last night, when I switched it on, I was greeted by a loud and regular "ticking" coming from the speakers - this happened regardless of settings on the preamp (I also swithed preamp to isolate the problem) - all source components were then disconnected, as was my subwoofer - the ticking only stopped when I unplugged the interconnects at the back of the amp (I also tried alternative interconncets, just to be sure these were not somehow responsible)

clearly I have killed something, and I'll be sending the amp to Sugden for repair, but my question is this: is there any way that connecting a valve pre could have caused this? the pre in question is a WAD Pre2 (very well built -not by me - & checked by an engineer) which is looks like a scaled down integrated valve amp with surprisingly large output transformers - everything worked perfectly when hitched together initially, and did so for three days, but it seems coincidental that my power amp should choose this moment to expire (I've only had the pre since monday), and I don't want to risk getting the amp back from Sugden & frying it again due to some unknown compatibility issue.

all suggestions / wild speculation welcomed

thanks in advance
MH