need help about cd/mp3 line in through guitar amps

[therethere]

My friend is using his line6 spider practice amp as pretty much a speaker for his vocals, mic'ed instruments and other keyboard stuff (rather than using a PA) and I wonder if its ok to do this, since I heard that putting certain instruments through guitar amps (i.e. bass) will eventually rip the speaker cone. But since this line6 spider amp also has a cd/mp3 line in, where you could play something that would theoretically also have the same freqs as the stuff I mentioned above, could this also damage the amp? I'm wondering about it because I have an old peavey practice amp with the same line in function and I'm wondering whether I will end up damaging the speaker cone...?

[fossiltooth]

Don't worry about it, dude. I'm sure if it breaks it wouldn't sound any worse.

Seriously though, you can play anything you want through any speaker. There are only two concerns:

1) Will it sound acceptably good for the situation at hand?
2) Are you clipping the amp or feeding the speaker more peak or average power than it can handle?

Don't crank it too loud and you'll definitely be fine. However, without proper metering, you'll have to rely on your judgment and sense memory to gauge "too loud". Unfortunately, it will take some trial and error (read: blown woofers) or years of experience to be able to develop a good 6th sense about what's "too loud, too long" for a given speaker/amp combo. So, in the meantime, either:

A) Err on the side of caution. and go quite like a mouse.(Sensible.)
B) Have fun, crank it like you don't care, and (eventually) blow some sh*t up. (F*ing Rock.)

The choice comes down to you and your personality. Neither way is "wrong". You could also try C) somewhere in between. That's probably cool too.

[therethere]

haha, alrite, if you say so, thanks i'll err on the side of caution first. once i make it big , i'll f***ing rock