subs for Sonus Faber Cremona M floor standing


My system includes Mac C2300, MC2102. I have it narrowed to the JL F113, Rel or SVS. I am looking to integrate it to the system... Not for the boom boom boom. This system is 2 channel for audio not home theatre. As the SF are amazing I just want to bring a little more low end back into the system. I was running Klipschorns biamped before this so I am missing the walls shaking ;)
erictye
One other thing that I forgot to mention in the Rel's favor....the hook-up scheme is IMO better than competing designs. The Neutrik connector allows a hi-level connection directly at the amp terminals, which allows the signal to be more precise to what the speakers are seeing at the amp terminals. I do think that this leads to a more "accurate" reproduction than taking the signal from the preamp, as in all other models that i am aware of......again, IMHO.
He's my dilemma: I already have one REL 505, and I can find another on 'Gon for about $1000. If I switch to the Velodyne DD12 (same piston size as the 505)I will want/need 2 and the cost will run to $3000+ if I buy them used.

My question is, will 2 DD15's truly outperform 2 505's? I mean hands down, no questions asked undeniably better?

Thanks,
Mike
Okay - just back from the Velodyne website where I found the Optimum 12. The Optimum 12 is a bit more than half the price of the DD12 plus - so what would I give up if I go with the Optimum 12 over the DD12? And is there any experience with the Opti 12?

Would the Opti 12 be considered better than the REL505?
Dear Daveyf: Options always are open, IMHO all depend on each one targets/priorities on quality level performance.

+++++ " my mains (SF GH's) are lighting fast and I know of no large driver ( we're talking 10" and above) subs that are quick enough to match these mains, " +++++

this link touch that " myth ":

http://www.soundstage.com/maxdb/maxdb061999.htm

Regards and enjoy the music,
R.
Dear Fundsgon: You can get these couple for less that you stated:

http://www.audiogon.com/cgi-bin/cls.pl?homesubw&1327021301&/Velodyne-DD-12-Piano-gloss-bla

http://www.audiogon.com/cgi-bin/cls.pl?homesubw&1328659975&/Velodyne-DD-12-Piano-gloss-bla

I think that you can make some money when you sold the REL.

Regards and enjoy the music,
R.