i guess try it and see, probably not many of us have tried to power an amp on 3.5. Are you talking about amps or volts? I have a home converter where i wired my amp in my room up to a 3.5amp 12v converter. Ran the amp perfectly fine although it was a bit under powered, the 13.8v converter would have been better.
I probably didn't answer your question, but have fun
The setup i described earlier works out just fine. I've down it twice. Once i have a 600w amp hooked up to a 15 jl audio speaker, attached it to my computer. Fraging someone never sounded so good!!! In my room i did the same setup but just for good sounds, so i daisy changed a 4x25w amp for speakers and a 200w amp for sub. Everything ran fine off the $30 radio shack power converter (not sure if i'm using the right word here). Either way it turned your wall pluggin current into 3.5amps pushing 12 volts (like a car battery) I would suggest the $50 dollar model which simulates 13.8volts. THE only trick is to get the amps to turn on, meaning you have to wire the "remote" (little blue wire usually) in such a way that when power turns on, it assumes the "deck" has turned on. I had to do this because my sterio was pretty primative. All i did to get around it was to hook up a loop from remote to power and added a fuse in a little fuse box holder (with two cables attached). Turning the amp off was as easy as swithching off the fuse (turning off the circuit) or just turning the power on the converter off, which you would always want to do if you weren't using the system anyway, because who wants that kind of power hanging out of your wall?. I lived in an apartment, and had the police visit me a few times on noise complaints, so it DOES work. And no, actually i never blew anything in the house with this setup, but turning on a space heater during winter blows my room fuse all the time!
