nalthien: Thanks for more detail information. And don't worry about waiting. Get what you need done first. These subwoofers will be available when you decide to purchase your sub. And when you get that sub, you'll need to do a subwoofer crawl test in order to place that sub where it will sound the best at your listening position. The correct location of a subwoofer is critical to your enjoyment.
I fully understand your preference for sealed designs to go along with your ESL panel speakers. I felt the same way for my Maggies. I tested out 3 sealed subs for my panel speakers and was surprised that only one sub passed all of my tests in what I was looking for in music reproduction. However, there are accurate ported subs, so don't let that dissuade you from putting a known accurate ported sub on a short list (such as Rythmik's top dog, the FV15HP -- $1339 for black matte or black oak and $1559 for piano black).
But more in line with your maximum budget, there are two sealed subs that come to my mind, and I've already mentioned one you should really consider for your large room … the PSA XS30se @ $1249 in matte black (I own their previous version, the XS30). The other subwoofer that is worthy of considering would be the E15SE from Rythmik. Price starts at $1024 for black matte, $1174 for black oak and $1349 for piano black (check with Rythmik on the shipping). While I doubt the E15SE will have the output of the XS30se and I'm positive it won't have LFE capability (it is a smaller box than the PSA and has a single 15-inch driver vs. two 15-inch drivers), it's an impressive sub that has accuracy written all over it. Jim Wilson reviewed this sub, along side the $1600 SVS SB13-Ultra (the subwoofer I own -- for music only) and Jim slightly preferred the Rythmik. That's saying something, because the SB13-Ultra is one terrific sub.
I'd also look at the Rythmik F15HP ($1074 in matte black, $1224 black oak and $1399 in piano black. This is the subwoofer I wanted to audition along side the SB13, but there was a 6 month back log at the time (over 1-1/2 years ago), so that didn't happen.
Music area: Magnepan 3.6, McIntosh MC2205 & C48, SVS SB13-Ultra, Oppo BDP 95 and assorted equipment.
Movie area: EMP Tek R5Bi, PSA XS30, Denon X2000, Oppo BDP 83.