2 x 15" sub design advice

Hi

Currently running with a single Rythmik F12, but looking to upgrade for music & HT.

I am very space (& WAF) restricted at the moment, but will be moving into a bigger place eventually, so I want to do a single sub initially, and just add a second for the bigger room when the time comes. Keeping in mind it is always going to be in a normal-sized living room situation, and only required to hit maybe -10db reference max...

My choices come down to either a single 18 in about 5cf, or a 2 x 15 in about the same. Given the displacement advantage of the 2 x 15 option, it would be the preferable option if I could get it to work within my enclosure constraints.

So, can anybody confirm what the minimum sealed internal enclosure volume would be for a dual-opposed sub using TC LMS-R 15" drivers, to make it worthwhile? Would 5 cubic feet work? If not, are there any other recommended 15" drivers with great SQ suitable for small sealed enclosures?

I will be using a 2 x 2400/4 watt amp (1800 RMS). Will I be able to power each sub driver with one amp channel initially, and then when I make the second enclosure, power each enclosure with one amp channel?
i.e. two individual amp input connections in each sub enclosure, so each amp output will be 'y split' into the two input connections of the sub enclosure (assuming y split Speakon connections actually exist??) Would this change the ohms load to the amp?

Thank you in advance for your help!

Nathan

Bump. Any advice?

I was considering the funk audio 2 x 2400 amp, but am now getting conflicting reports on its real ability. So not sure what to do really. I assumed it would be enough, and Funk says that it measures very well. What REAL power do I need for 4 cubic feet?

Anybody know if the new Dayton UM15 driver is a competitor to the LMS-R 15? Keeping total driver and shipping costs under $1K saves me 15% in import taxes!

Approximately 2500 cubic feet.