Im wanting to get into some live acoustic shows, and i was wondering, is it necessary to have an actual acoustic amp? I've plugged into my electric guitar amps, but is the sound actually better through something like one of those roland or fender acoustic amps?
I like my Fender Acoustasonic and have been very happy with it for shows in up to medium sized rooms, but I wouldn't say any other decent amp wouldn't do as well. You might try it out a few times and if you get serious about it consider moving up.

The best thing to do would be to take your guitar in with you to a dealer and listen for yourself.
Take a look at Genz Benz Shenandoah Series. These are built for acoustics. I have the GB Shen Jr. and it is truly amazing. Full, clear, loud, and no distortion when cranked up.
--- Joe ---
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depends on the setting. is this a coffee shop, birthday party, small or no stage, no drums type of thing? or is it a full band setting in at least medium sized venues with a crowd of 100+ type of thing? if the first scenario is true then I highly recommend the Fishman Loudbox Performer or like Auriemma said the Genz Benz ones. I think the Genz Benz ones in the medium to upper range cost a bit more than the fishman, but you do get wha you pay for with this type of thing.

if the second scnario is true then dont bother with an acoustic amp. Just use whatever PA system the venue provides. there will be tons more gain on tap, stero, less equipment to carry, and no money wasted.

Dr. Z Stangray
G&L ASAT Classic (Ron Kirn Custom T-Style coming soon! ronkirn.com)
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Taylor 314ce
If you decide to bring your guitar in and have a play on an amp, I'd suggest playing till your hearts content then finding another person in the store who can play well and ask them to play while you walk around and see how it sounds to an audience. I wouldn't worry about it as much with an electric guitar amp cause you get what you get with those, but you might be hearing it differently with the acoustic on your lap.
hartke ac 75 or ac 150... i have the ac 75 and it is awesome.. tons of built in features... great price... cant go wrong