On Rel subs: Which are most musical?


It appears that rel makes some of the more musical audiophile quality subwoofers.
My question is which rel model do I go for? I am looking for a sub that isn't too big, is not sloppy but tight, blends in and fills the room with a natural sound that makes it sound as though it's live, in a very articulate realistic sounding system.
For what I am looking for do I look for a big size driver such as 15" or a smaller driver such as a 10" or 8" driver? Does a two driver sub do better than single?
What are the pros and cons between the two?
Does a smaller driver give me tighter bass and a bigger one give me lower and fuller bass?
pedrillo
Anyone put forward firing sub right between main speakers? I asked about forward firing because I wouldn't want it to fire downwards, I would want it to play music not massage the floor.
Bass from any sub (on the floor) will "massage the floor" regardless of the speaker orientation as bass notes crawl along and are reinforced by any nearby flat surface. An acoustic unavoidable reality. I have both front and floor firing subs (2 RELs in the main listening rig, one front and the other floor firing, and a large Mackie in my recording studio area that has both a front passive radiator and a down firing driver) and they sound very "musical" when placed and driven properly.
Are you saying that in this aspect there is no difference betwen front firing and downfiring subs? Sure, what you say about reinforcement is true, but in full range speakers bass woofers don't normally fire downwards.
just be careful with the xo. even when you set the xo at 30hz, the rel T series are -6db at 55-60hz

so ime, matching mains that are -3db at 40 or even 50hz will not integrate with rel t series.
@murphythecat

In which case a miniDSP unit would provide a better crossover. Certainly more flexibility. :)

If the sub doesn't come with an EQ capability built in it's pretty much mandatory in most homes.

Best,

Erik