I have my XTANT 1001 which puts out 1000watts that im getting rid of. I bought if for 1200.00 and asking 600.00 for it. It is in mint condition and still have warranty on it. call me (425) 985-5415 or email firstname.lastname@example.org if interested.
You should be ok anonymous with that size alternator for sure. Im working with 80A and im gonna be running 850-900rms so we will see how it works out. Im using a batcap model 800 stereo battery for backup.
a: if that's 105A stock rating, your car probably uses most of that already for things like heated seats, AC, wipers, lights, fuel injection and ignition, etc.
b: if it'll work will totally depend on how hard you push that amp. 700wRMS is 70A of current, which is a lot of drain on a 105A alternator. now 70A is at peak output though, so if you're not going to drive the amp hard, it will draw much less than that and yeah you may be fine.
Seems like you have no choice these days but to upgrade from the stock alternator if you play your systems loud and have the volume high. One question i had was like what is considered keeping the volume and draw down?? Like lets say for an alpine deck..0-35 volume. What is considered average listening and what is pushing the amp hard?? I use to keep my alpine around 17-20 average.