I owned a T400 several years ago. It was a fantastic sounding amp. My only concern would be the output transistors. In the T series amps Threshold used IGBT output transistors, which are now obsolete. So if one of the transistors should bite the dust (remote, but always a possibility), the amp would need a quite extensive rebuild. As I'm sure you would have to then replace all of the transistors as well as any other ancillary components.
You may get more detailed information from Jon Soderberg at Vintage Amp Repair.
Cheers,
John
You may get more detailed information from Jon Soderberg at Vintage Amp Repair.
Cheers,
John