I’ve had the Stereo 100 for ~3 years now (driven by an RP7), and had no plans to upgrade... now you have me interested in this upgrade. Any details regarding what they do in this dark upgrade? Already very pleased in the bass performance of the Stereo 100, to improve on that would be impressive. Regarding the Stereo 100, it’s dynamic, detailed, but "muscular". Doesn’t break a sweat with music that would sound disorganized or frenetic on other amps. Love the treble decay, which tubes seem to get better than SS IMO. Stereo 100’s bass better is superior in quality to the SS Parasound Hint and NAD 388 that preceded it in my system. +1 to excellent Rogue customer service as well. They’re good people. Edit: my listening tastes are like 70% jazz, the rest fusion, afrobeat and rock, with a bit of female vocals (inc. Nina Simone, Sarah Jarosz). The Stereo 100 seems adept at all of those, and is versatile. Oh the Stereo 100 is super quiet in my hands.