Go for sub or larger speakers?

In most cases, adding subs will cost substantially less than going a model up with main speakers, and get you better bass. Also, since the subs are typically active, you are giving you amp a break with the subs.

What I did with absolutely stellar results is this. Get 2 very fast subs (I have JL Audio 113). Run 2nd output from your preamp into an external crossover (I use the cheap NHT X2). run the low pass signal into a SVS (or audessey - some unit), 2 channel sub equalzer in discrete stereo mode. Dont mess with your mains signal - run them at full range. Play around and do some in room measuremt to find the best crossover point for your low pass filter. Apply bass EQ to your stereo subs.

Ckoffend - you are dead on. I had 15" Revel B15s and the 13.5" JL 113 in the same room, and although the Revels go somewhat deeper, the JL's are faster and easier to integrate.

Martykl, I'm sure in some systems your approach will work better than running the mains at full range. Its a trade of between smoother integration and the degradation of running the mains signal through an additional active filter. If I had gone down this path, I would personally not have used the NHTX2, but get a higher grade crossover like a Marchand XM44.

This may be pure snobbery because I have no proof whatsoever an XM44 sounds better than the cheap NHT, but I would not like the idea of running my main signal through a cheap crossover when I have some very high grade electronics upstream and downstream. (Sort of the "weakest link" theory). Your appear to be owning some fairly expensive kit yourself, so I would definitely try out a higher grade crossover sometime and see if you get any improvement.

Marty,

You could pick up a used Theta Casablance III with 1 Xtreme card for about $4,000, and use it in a 2.1 application. I own a CBIII with XTreme card so I can give you some advice here. From what I gather you want to consolidate boxes, and need four things; Preamp, DAC, EQ and Xover. The CBIII will not give you EQ, so you still need yout SMS-1. The Xtreme card is a good (10 year old) DAC in a MCH application, but a modern 2 channel DAC beats it hands down (I have a PS Audio Perfect Wave which is a better DAC). Xover flexibility is second to none in the CBIII - no issues here. However, your LS25 is a far better preamp than the CBIII (I use a Theta Six Shooter for preamp, which is far better than the analog bypass in the CBIII). In summary, depending on what DAC you are currently using, you will very likely take a big sound quality hit with a CBIII, still have a two box solution, all for the questionable benefit of having a good Xover in a box 40lbs box (with I bunch of features you don't need).

A far more promising alternative is to look into the TACT 2.2 digital preamps with build in EQ and Xover. This has all the four functions you need in one box. I suspect the (optional) buld in DAC is the weakest link - but not to worry, it has digital out so you can hook it up to an External DAC. The only wildcard here is you are going from volume control with your LS25 tube preamp, to doing it in the digital domain. This would be anathema for purists, but since you are considering a CBIII and are not loosing any sleep over using a cheap Xover in an otherwise high grade system, obviously you are not a purist (I say this as a positive).