An interesting and timely question for me. Have moved to a solid state amp regime (Gallo's sub amp and a homebrew UcD 400 pushing Gallo Ref. 3.1's). Had been using a TacT 2.2x for simply a DAC & room correction, with its analog outs going into a tubed Melos SHA Gold Reference Maestro preamp (using pinched-waist 6922's) for the express purpose of "warming" the sound. A couple of days ago, I tried the system without the Melos, using the TacT as a preamp, and was a bit surprised at an audible increase in "clarity." Still listening to it that way and am having second thoughts about using a tube buffer, which is the Melos in my system. I suspect the phenomenon may be highly system dependent. Of course, YMMV. Cordially,