Man I love having a modded DCX in my system. The amount of control it gives me is amazing. Recently I got a Scott Nixon Tubedac from a member here on AC, to hook up to my Satellite HDTV audio feed, as a way to deal with the harshness, distortion, and clipping that is frequently encoded directly into original signal. So, I have my Audio-GD DAC8 for my DVD's and Blue Rays, the Nixon for HDTV, and the Bolder Super Duet for my music.
Of course I have to A-B the new DAC against my Duet, and while the SN does some nice things in the mids, the Duet just spanks it in bass power, sounding much more solid and present. Pretty much what I expected, based on the last time I owned the tubedac a few years ago. But it still suites my purposes just fine for the current setup.
I did think that the texture and detail of the bass was pretty good, just a bit soft and rolled off. So on a lark I decide to use the DCX to simply boost the bass region by 0.6 db, and the results were very impressive indeed. The SN sounds a lot more balanced and richer, putting it much closer to the Duet in these areas. I think the Duet still has better dynamics and better focus/separation (with similar "lack of harshness" in the mids/highs), so it stays as my primary music source, but I think it's interesting that a little bit of shaping in the frequency domain can address an area like this so easily.
I guess the beauty is that I can adjust things to get the sound that "I" like, and I truly love that.
Only caveat - protect those tweeters! I had my tweeter amp oscillate on me during power down, and it took out one of the ribbons. Replacement is on the way, but I've had Wayne at Bolder make a speaker-level Auricap Capacitor in-line attachment to protect it from any future funny business from an amp.