(non-remtote) Quicksilver linestage owner here. I think the quality is very good. I noticed that there is a bit of crosstalk between channels. For instance, I can faintly hear my streamer and turntable playing on other inputs when I switch the selector dial. But since you only ever listen to one source at a time, it has not presented an issue for me.
As for the sound, it adds a bit of tube warmth and richness without ever sounding syrupy.