I have had the 12/90 preamp/amp combination and upgraded to the 20 and a second 90 bridged. Only when I went top of the line in MIT cables(shotgun EVO interconnect and 850 CVT speaker cables), dedicated power lines and full complement of MIT line conditioning did the system show its full potential. The Spectral gear is incredibly revealing and will be bright sounding with less than the best. Musical recordings will be "musical". Bright recordings will be bright. It will reproduce the recording very accurately. The speakers are very critical as well. I have Avalon Arcus and the combination is well matched. Of course the Avalons are made to mate with Spectral gear. I had Vandersteen 3 and they did not have the resolving power in the mids to complement my Spectral gear. I have yet to upgrade to the Spectral digital. I currently use a Theta Jade/GEN Va with single mode. By the way, the dedicated power lines and dedicated ground was by far the biggest improvement ever in my system. I am now hearing details on recordings that I never heard before. I'm talking about recordings that I have listened to for years and years. Hope this helps!! Tim