Hi Leeph. the paradigm servo 15 is a very good sub, however the x-30 crossover is rather mediocre at best and in my opinion defeats the purpose.I believe the sf-1 has 2 pairs of outputs. You can run 1 pair to your amp for the main speakers and use them full range[no crossover] and the other pair to the x-30 and "try" to blend in the response of the sub with the gain on the servo amp.This approach is a rather labor intensive proceedure as the location of the sub in the room is now much more critical as far as making the mid and lower bass sound cohesive with the mains.The adjustment of the phase pot on the x-30 is a very big plus for this excercise.You did not mention the main speakers you are using but adding a little foundation or bass weight can be an exercise in frustration.I personally would dump the x-30 and buy a better crossover.There was an audio research e-21 listed here on the GON recently at $400.[great price and great crossover]! the audio research crossover is a purely passive crossover for the mains and active for the sub.It employs 3 12ax7's and the turnover frequencies can be changed with capacitor kits from audio-research. The bryston 10b is another very good crossover that does not add much of a "signature" to the main speakers and is light years better than the x-30.Once in a while you will see an old dalquist[can't remember the model #] crossover surface periodically... this is a also a purely passive crossover for the mains and really is a great crossover if functioning to spec.
Best of both worlds?
If you used a powered sub (such as a Vandersteen 2Wq w/ an external corssover) along with a tube amp, would you effectively have the "best of both worlds" or would your SS sub amp get too much of a low-end sonic signature from the tube amp.