I switched from a McIntosh MC2205 amp (solid state, 200wpc) to the GM20 to go with my old (14 years) pair of ProAc Studio-2 speakers -- man what a difference, the speakers just came alive. I did listen to the 1SC but not with any tube gear, so I can't say. The SC1s seemed to be very focused and has a much smaller soundstage than my old studio-2s. But the studio-2s are about twice the size of the SC1s. I also own Graaf's 13.B tube preamp but I find that the lowend noise is better when GM20 is paired up a SS preamp such as a McIntosh C32.
