earth ground disconnected or not ?

Grisslehamn,
You know I never thought about that, besides I wouldn't do that. If too low, the fuses blow, if too high, the units blows. What I have done, is to substitute the stock fuses for those expensive German "gold"-fuses and, sadly, perhaps being tin-eared, I heard no difference whatever.
Cheers,

Grisslehamn,
YOu may want to consider one more option;

Dedicated earth ground for your audio system only. The medical grade outlets offer this feature, where the outlet can be ilsolated from the system or house ground. Depending on where you live in the country, and the age of your house, your house ground may not be that effective to begin with.

This is among the quietest of all the options. One has to be careful, if making the dedicated ground a wet ground, since you'll need to have a wire gauge large enough for your panel.

Dedicated earth ground for your audio system only. The medical grade outlets offer this feature, where the outlet can be ilsolated from the system or house ground. Depending on where you live in the country, and the age of your house, your house ground may not be that effective to begin with.
05-15-08: Johnss

Johnss, if you are referring to an isolated equipment safety ground that is not connected to the main electrical grounding system, that is not acceptable anywhere in the US.....
It does work great for hunting fish worms though.....

The earth shall not be used as a means to carry fault current back to the source. The earth is a poor conductor.

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If i disconnect the earth(ground) will the sound be better ?
Grisslehamn

Possibly if you are experiencing ground loop hum problems.
You could set yourself up with a safety issue though. Especially if you are feeding your equipment from more than one circuit and the circuits do not share the same Line, leg, from the electrical service panel. It is possible under the right fault conditions that a difference of potential, voltage, could exist between the enclosures of two pieces of equipment as high as 240Vac. That is if both pieces of equipment have their safety equipment grounds lifted.