I would imagine it would depend upon the current draw of your amp (which will be related to the type and output RMS of your amp).

Actually I 've got two amps : one 4 x 130W (4 speakers) and one 1 x 600W (Sub)

I guess that might be a bit too much. Can I solve this with a cap?
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Riocar 80gig S/N : 010101580 red
Riocar 80gig (010102106) - backup