I did consider the Mephisto. What scared me is the lack of North American support.If you have any hesitation about "musicality" (whatever we all mean by that term) with the 3060, then I think you already have your answer. Any such hesitation, I believe, will only gnaw at you more over time. From your hesitation I deduce that the Boulder is not the right amp for you. (And unless dCS has changed their house sound, I do not think that dCS components are on the warm side of the sonic spectrum.)
I assume you want to stay with solid-state. Have you considered a Gryphon Mephisto? I think that amplifier would give you the bass and low noise floor you want without sacrificing "musicality."
I am also thinking about the dartzeel 468. I spoke with the NA distributor today - very nice guy. The problem there is I need to fly to the East Coast to hear it. Oh, and then there's the price. It has taken me weeks to justify the cost of the 3060.
I suspect that I'll like whatever I get. Initially. It'll be over time that I either 'want' for more or am 'happy'.
I am also mindful of the preamp decision. I currently run the dCS direct into the d'Agostino. I am going to get a preamp this go-around. I am inclined to get a tube preamp with the VTL TL-7.5 being the most likely