I have an RCS 2.0 that I use with a sub. I set it up as one would without the RCS (position, phase, and amplitude) and then used the correction on the whole system. I'm happy with the results. -- As to its use as a preamp, I compared the internal DAC to my Bel Canto 1 and thought it was less mellow but pleasantly clear. I removed my preamp (AE-3 sig into an SE-1 sig with Sophia 300Bs) and immediately put the preamp back in the system. YMMV
