2 Subwoofers or 1?

The guys I hang with enclose the slot on RELs. Bottom ported or downward firing subs are as old as dirt. You can't decouple them. If you don't decouple, you screw the timing up at the seated position. There is a SUB signal coming to that position from the floor a lot quicker than through the air.. It's called smear. When you eliminate the "smear" the BASS not the sub clears right up along with lower volumes in the mids and highs.. I call it HiFi. You never notice it until you decouple.

I use an air ride system. OHM design.. It's 15 years old. I started with 2 8" IB subs. I use 8 12" OB servos now. GRs. I don't know of anyone that doesn't use Rythmik plates or at least DSP for the Bass. You better know what your doing if you want it to sound GOOD. Room first, then see if you need subs. I have a couple of rooms subs don't work. They're just too small after 200.00 dollars of room treatment..

Terrific! So you had a chance to audition with what looks like a very wide selection. 

My only experience with REL was the British made Studio III, a two-10" downward facing. We eventually scrapped the manufacturer's setup process and ran it on its side along with a few other changes.  

Welcome to the deep end. All the best with your search.

Many. It's Audio Advice in Raleigh. Audioadvice.com. This is my first time thinking about subwoofers, so I am really starting from scratch. I appreciate all the advice.

Howard

A subwoofer/s system is a separate component which are more often designed to accommodate most future speaker or room changes.

For the sake of a direct comparison does this dealer represent any other subwoofer manufactures?

I have a similar room and have 3  S510 subs so IMO given the 2 choices I would  say neither...the  5tx is bottom firing and I wouldn't want that at all,and 1 9x is not enough...I would wait till funds permit and then buy  2  7X or 9x...or 2 used Rels like the previous I series

Three are better.

Regards,

Dan

I don't think two of the T/9x are in budget....

I hear you. You really want two subs, front firing, located near your little stand mounts. You will be crossing over fairly high and the subs will make your imaging work much better. The smaller sub does not go that low but I'd take two of those over one of the others. You can get the two small subs first then get a larger single sub to work the very bottom frequencies some time in the future. 

Two (or 3) smaller subs located strategically (multiple subwoofer crawls) would give smoother bass response in a primary listening position than a single sub.

I don't think two of the T/9x are in budget....

Two T/9X front firing located as a stereo pair inside of your loudspeakers.