I have never been convinced that fusing both sides has any effect on sonics whatsoever.
Technobabble justification:
I did a quick measure of a 5 Amp fuse and its resistance was 0.3 Ohms. Add 0.1 Ohms (worst case) for each end contact - that gives an additional (worst case) 0.5 Ohms in the power transformer primary circuit.
In a 240V to 25-0-25 transformer this reflects into the full secondary as an additional 0.02 Ohms.
In a 110V to 25-0-25 transformer it reflects into the full secondary as an additional 0.1 Ohms.
Either way these are swamped by the actual resistance of the secondary windings.
If you think you can hear a difference and are happier with a single (active) fuse - feel free, BUT I suggest its purely psychosomatic and that you only hear a difference because you had convinced yourself ahead of the actual listening that you were going to.
I could as easily argue (for the sake of arguement) that the tiny increase in total effective secondary resistance will very marginally decrease the peak current flow in the secondary and the reverse recovery transients generated in the rectifier diodes. This would reduce the resultant radiated RF, and reduce the ripple currents in the filter caps, hence relieve them of some stress. From this point of view the additional fuse should make the amp sound better - hows that for a juicy rationalisation?
I the end what sounds best is what you are happiest with. It doesn't have to make sense.
Cheers,
Ian
Mmmm, Ian, you seem to be getting into the old "what measures good, must sound good" argument!

Let's go back to the design of the AKSA ... I'm sure as an EE, you could develop a perfectly believable line of argument why, say, a 500VA power transformer for the 100s would make them sound better than the 300VA trannies which Hugh specifies (bigger means less saturation of the core, more reserve for transients etc etc). Yet Hugh specifies 300VA trannies because he says bigger ones cause the 100 to lose some "nimbleness" ... kinda like there's more "inertia" in the bigger trannie which stops it reacting as fast!!

However, I certainly agree that it would be enlightening to do a listening test with identical amps, one double fused, one only 'active fused' ... and one with no fuse at all, just as a reference.
Regards,
Andy