How did you determine the power supplies were OK if it blows the fuse at 30v on the mains?
WHen an amp blows fuses, the first thing I look for is shorted outputs, if they are not short, then I look for shorted main rectifiers.
How about a main filter that is real leaky over half its voltage?
REmember this is a single supply power amp, so there is a speaker cap. MAke sure it is not shorted, and of course work without a load.
I'd connect an ammeter in place of the fuse. WHy waste fuses. You can see the current ramp up before you even hit that magic 30v - or whatever - and back off instantly.
SImple enough to isolate things, pull the wire off the power amp card that supplies the +92VDC. If it still blows fuses, you have a main PS problem. The LV rails are derived from the +92 in the PA.
My approach would be to disconnect the +92 from the rest of the unit and see if the PS alone draws current. If so, does the rectifier alone draw current - ie no filter cap. If so does the PT alone draw current.