IMHO, Jeff Rowland hit the sweet spot between musicality and transparency in the mid to late 90's with the Model 2/6/8/9 amplifiers. Earlier designs tended to be warmer, while later designs tended to be more transparent. The best JRDG preamp I've ever heard was a Coherence II, which I think also went back to the late 90's. As for preamps, well, though Jeff's designs are good for solid state, I don't know that I can listen to a solid state preamp anymore, I gotta have tubes in my preamp.
That's just my $0.02.
That's just my $0.02.