That Image Dynamics sub looks pretty awesome. Definitely sounds like a great sub, but while I am primarily focused on SQ, I do want it to be decently loud when I feel like getting a little crazy. Would that have what I want in that regard? If so, that may be the ticket.

Lol, damn you for adding another choice in my already difficult set of choices. I'm throwing the two ED subs out as I'm trying to save space here so I'm down to:

Fi SSD10
RE SEX10D2
Sundown SA-10 D2
Image Dynamics IDQ10V2.D4

That particular Image Dynamics sub is discontinued

You are correct!

However, they seem to have this one available:

http://www.woofersetc.com/p4993/ID10...-Subwoofer.htm

In dual 4 and dual 2 ohm versions. Would this be a comparable sub to the one previously mentioned?

According to this post:
http://www.diymobileaudio.com/forum/728931-post5.html

The guy hit 142db on that 10" sub!

Also, why would one choose the dual 2 ohm version over the dual 4 ohm and vice versa?

Dual 4 ohm or dual 2 ohm that is the question. One isnt better than the other its all about wiring configurations. What is your amp stable at? how many ohms do you want to run at? If your amp is 1 ohm stable and puts out 1600w rms, that might be to much power for what u are trying to accomplished. so maybe you want to run at 2 ohms.

a dual 2 ohm sub can be wired to 1 ohm or 4 ohms
A dual 4 ohm sub can be wired to 2 ohms or 8 ohms.

yes that would be the closest to the before mentioned sub

that guy was measured at 142 db with 2 10" ID'*

Ah, I missed that. Still pretty impressive though.

Makes sense. My amp is stable at 1600W @ 1 ohm. It will handle just about anything.

At 4 ohm it will run at 550W, which could possibly be too low for a 400W RMS sub. I've always heard its best to overpower your subs. I might be better off going with one I can wire to 2 ohm. That'* how I wired up the R12 in the Bonneville.

What do you guys think? With the amp I have, dual 4 or dual 2 for this particular sub?

I think Dual 4 ohm would be smartest. If u run the sub at 2 ohms it will have good output. wiring it to 1 ohm would be all out balls to the wall. all the power your amp can produce. Ur not interested in SPL and wiring the sub high than your amps minimum impedance will give your amp longer life.

yea thats still pretty darn good

That sounds like a great idea. That'* where I was leaning, and you confirmed how I felt.

I'm really not interested in SPL. Obviously I want loud bass, but I don't care for the kind of bass I'm getting out of my current 15" that makes it harder to breathe. Just something that would go well with my classic rock, alternative rock, some country here and there, techno, etc. I listen to very little hip hop and rap as it is. I've discovered for hip hop and rap, this 15" is the ticket, but its not tight and refined enough to play the rest of the music I listen to, at least not for my tastes.