Speakers blow because of distortion (bad signal, clipping, wrong frequencies) not overpowering (except in extreme cases).

You can give a 5-10W speaker well over that and it will work fine... but the minute you give it too much bass or the signal gets distorted it's gone.
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10+40 Gig Mk2a... with Tuner. S/N 040103784 || 2001 Jeep TJ, 60th Anniversary Edition