I am not sure what to say. Last time I got shot up for advice based on what was popular when I was into the car audio back in my day.
A 2 ohm speaker has less resistance so it will alow more amperage to flow through it at a lower voltage.
20 volts at 2 ohms will flow 10 amps. 20v * 10a = 200 watts.
20 volts at 4 ohms will flow 5 amps. 20v * 5a = 100 watts.
Two 4 owm speakers in parallel equal a 2 ohm load.
Two 2 ohm speakers in series equal a 4 owm load.
Given your amp is rated for two 2 ohm per channel at 350 watts I would go with the 2 subs myself. Bridging it and running them in series will still give you 350 watts each.
I dont care what any one says two 12 inch at 350 watts each will move more air than one 12 inch at 700 watts.
Plus with two subs you can always add a second amplifier when you get one!
If any one says you dont need that much power tell them, Piss off! Your too old!
And you can quote me on that even though I am almost 35 years old.
Make loud noise, Live care free, And play nice with the girls, or you will regret not having done it later! I promise!
The amps I had were rated to run 2 ohms per channel or 4 ohms bridgeable. They were what was called at the time a three channel configurable design. that is, in stereo mode they could run a four ohm load at each channel but still run a single 4 ohm sub across the bridge connection. Two input channels three output channels.
The negative of one channel shared a common internal connetion with the positive of the other channel.
When I ran 2 matching subs on one amplifier the center connection point to the amplifier could be disconected and there was no change in the sound. It only needed that connection for stereo sound. Mono mode did not care. Exspecialy at the low frequency end.
I still say the subs in series do work.
Just do what your ears tell you sounds right! You will be much happier, pick up more girls, and the other guys will be a bit more envious!
Isnt that what this is all about anyway?