@rodman99999 btw: I’ve had HI-FI Tuning’s fuses(Gold and now Supremes) in my Cary monoblocks’ mains and B+ circuits, for over 12 years, without a problem. That’s not counting when the occasional tube took a crap and the fuse did it’s job. Then again, that’s just my own(one person’s) experience, and- why should you take my word?.
It matters where the fuse is in the circuit. Please tell us where it is located, its rating and what it is breaking? Are you sure its in the DC HV path?