Playback Design with Hifi tuning fuse

My experience would be stop playing with fuses until you get direction from the manufacturer.

I'd buy half a dozen of the 40$ fueses and play with 'em until I figured it out.

Cheap fuses don't always blow when they should. HiFi Tuning and other similar types blow when they should. Slow blow fuses are supposed to allow momentary rises of current above rated value provided they are very short in duration. If your slow blow fuse that came with your unit operates fine, then stick with only slow blow fuses. If you want to use a HiFi Tuning fuse, use one with the same rating, not a fast blow type.

Like Raquel says, talk to someone at HiFi or a dealer rep. Also, be prepared to give them the info, if you can, from the circuit board (the printed info next to the fuse holder) as it can help narrow down just what the designer intended. When I replaced two fuses on an amp I had, the info on the circuit board did NOT correspond to what one of the fuses were. The rep told me this happens more than you think and he sent out the correct fuses and I've never had a problem.

On another note, I stumbled upon an article on aircraft fuses and the author tested them and discovered that when a lesser make fuse reached 80% of thermal limit, repeatedly, it developed a memory and blew at the lower setting. I wonder if this might be happening in audio products as well as there are lots of stories out there about continually blowing fuses that no one can figure out.

Good luck in your search.
All the best,
Nonoise