Magtech amplifier over heating.

I had a Sanders ESL amp for almost 6 years and never had a problem with it.

Roger and Angela are fantastic people and will always take care of you. Also their product has a lifetime warranty.

Sorry you've had problems, but just be glad that you had this amp and not some other that only offered a few years of warranty and would have cost you to fix it.

negotiate with Roger so he'll give you another amp and your amp he'll keep on fixin' indefinitely. this will save lots of money shipping it back-fourth. test Roger if he's good enough to make that happen.

You need to know that ThermalTrak have had a bad reputation for failures and SOME models were allegedly discontinued a few years ago.

I suggest you read this thread http://www.diyaudio.com/forums/solid-state/237929-thermaltrak-transistors-have-been-discontinued.html for a typical discussion, but keep in mind it's also true that some other models may be back or are still in production, for example see http://www.onsemi.com/PowerSolutions/product.do?id=NJL3281D

Then read up http://www.whatsbestforum.com/showthread.php?16924-Viola&p=306879&viewfull=1#post306879 on Viola claiming to be getting "low yield", meaning, a lot of dead wood; but the units that did pass QC have had no problems.

The point being is that you should talk to Roger and figure out best course of action, loaded with this info: what models is he using, what's his QC process, why so many failures in your case, etc...

I have also found out through the years that the more expensive amplifiers tend to have a lot more device-matching done on them, and a lot more QC; but this statement is not universal (e.g. have witnessed all too many expensive tube amps blow up and take speaker drivers with them).