amp hiss impact on speakers

geez, and I presumed only an SR fuse could possibly extend the life of a tweeter.

Definitely overuse of carbon.

@almarg   Intersting post. On my ss amp, if i listen very closely to the tweeter, even with the amp in the off mode( which in this amps case still is actually in the stand by mode...unless it is actually unplugged from the wall) I can also hear this very very faint hiss. I disconnect the bi-wire cable that connects to the tweeter side in this case, while leaving the bass connection still attached, and the hiss goes away. No issues. 
However, if I were to leave the connection, and I suspect this is what the OP is asking about, the tweeter would actually be playing 24/7. While it is clearly NOT being over driven...far from it, like you stated, the tweeter motor is still active. IMHO, this would lead over some extensive time to a premature aging of the part.

IMHO, this would lead over some extensive time to a premature aging of the part.

Hi Davey,

It seems to me to be self-evident that there must be **some** power level, other than zero, below which continuous application of that power to a tweeter will not significantly affect its longevity. Assuming, of course, that the frequency content of that power is within the tweeter’s rated bandwidth.

Based on the assumption I stated earlier, that the hiss level the OP described corresponds to an SPL of 40 db at 1 meter (and I would feel pretty certain that the actual number is much less than that), and based on the specified parameters for the tweeter I used as an example (which is used in a small stand-mounted speaker), it would mean that the tweeter is being driven by one five-millionth of its rated power handling capability.

Given the assumption that there is **some** power level, other than zero, below which continuous application to a tweeter will not significantly affect its longevity, it seems to me to be a very safe assumption that one five-millionth of rated power handling capability is small enough. And again, the actual number in this case is probably much less than that.

Regards,
-- Al