What's going on with Synergistic Research fuses?

I live in California and a couple of weeks ago we had strange lightning storms that started the many fires burning in the State.  It also fried the fuse in my Pass XA30.5.  I got the amp second hand and it came with a SR Blue fuse.  I called Pass and they recommended a very cheap fuse which I ordered and installed.  Because I was curious, I took the SR sticker off the old burnt out fuse and found that it was a very cheap SIBA brand fuse underneath.  It is clear that SR is either not making the ceramic casing for this fuse or using the SIBA fuse and then doing stuff to it.  At the very worst, it's just slapping a sticker on it and charging a ton more

The thing is, I'm pretty sure I could hear a difference for the worse when I installed the cheap glass fuse post lightning storm.  Could it be that SR is modifying an existing fuse to make it sound better?  Maybe some more technically minded folks here on the forum could help me understand

thanks!