Fuse size

It calls for a 2 amp fuse. You use a 2 amp fuse or LESS.  Never up, always the same OR down. 

Clean the fuse holder surfaces. If it's crusty, rusty, or otherwise, use a small flat blade screwdriver, scrape the surfaces and then clean with rubbing alcohol.  Blow it out with low (dry) air pressure in a can or a compressor.

If it's one side only, swap sides, left to right. If it continues on the same side, BUT not the same speaker, you might have an oscillation issue with one channel on the amp..BUT always inspect your cabling, for problems and TIGHT, CLEAN connections... Isopropyl works fine..

Regards

Increasing the fuse size because it blows is like shutting off the carbon monoxide alarm because it's giving you a headache.

Thanks , I'm pushing them with a pioneer vsx-D603S 1994 really sounds great 

Last time they blew both went at the same time, seems odd, normally I have that pioneer in my game room pushing  2 fisher and 2 kenwood speakers with no problems, loud enough to not be able to talk and still clear