I heartedly agree with almarg's position. In the big scheme of things, 1.7A difference is not a whole lot when you are looking at a 6.3A reference point. And it really varies depending on manufacturer. A 6.3A fuse is relatively equal to 756 watts of energy. Bumping this up to 960 watts with an 8A fuse is likely not going to make much difference of where the fuse breaks/melts, especially since this is probably going into an amplifier which will use a lot of current anyways. I would say that using a 10A or more fuse may start to border on the "too much" scale. The bigger amps that use 10A or 15A will have a lot more power supply and circuits to spread the energy around before it hits the "too much" threshold.
I have seen some manufacturers that are right on the edge of what the amp will use (watts plus overhead/waste) and others that are 2-4 amps above what the electronic device is scoped for.
Generally speaking, a higher amp fuse is a thicker wire with less resistance. It will allow more current and faster current through to the device and the result can be improved dynamics and punch/power in the sound. There is a point where it doesn't make much difference.
john421 likely purchased one of the clearance fuses from Parts Connexion. These are probably either Hi-Fi Tuning Gold or Hi-Fi Tuning Silverstar, selling for around $15 or so.