Rel T9 or S2

wmbode-

I have heard the "B" and "T" series from REL.
Easily, the are the best and most musical sub(s) in the business, IMO.

B- Britania series are larger than the more compact "T" series.
it has been rumored that the "T" models and newer are partially made in china? If this is true, seek an older REL from the U.K. build.

I have not spent any time w/ the "S" series. 
REL subwoofer(s) are very easy to integrate into any system, tubes or solid-state, and sound incredible.  Keep me posted & Happy Listening!

The S2 and the T/ 9i are close in price so I was just wondering what justifies the $250 price difference

I would not know- consult your dealer/retailer and maybe they can provide an answer?  Keep me posted & Happy Listening!