i am only familiar with the sophia 1 thru various comments made on sites such as these. i have auditioned the sophia 2s at length. perhaps an amp that presents in the neutral to neutral to slightly warm [vtl] rather than highly analytical and/or lean [older models of bryston, krell, ayre, for example. though the most recent models may be excellent].
i favor pass labs amps, the x###.5 series is wonderful with highly detailed speakers such as the wilsons. depending on your budget, room size, room acoustics and your normal listening volume, you have more than a few choices. tube amps may also be excellent, but if you go tubes, pay close attention to how defined and quick you require the bottom end to respond. mcuh depends on the rest of your system, which includes the cables [ imo, cables are not frosting on the cake, i consider them as integral and key as any component.] frosting on the cake IMO me is if the component you have chosen with your ears actually looks pleasing to your eyes... and if the remote control is user friendly.
back to pass labs amps: consideration of impedance issues with some tube preamps should be noted.
if the sophia 1 has a somewhat bright highs, you may want to investigate the recent pass amp series XA###.5 which runs fully in class A or the older XA [no point 5] series , which is also a bit warmer than the x###.5 series [but perhaps slightly less transparent and nible IMO, though this may not be an issue for the sophia 1]. pass labs can best advise you various differences among their models in terms of performance. they are very familiar with wilson speakers as are many amp mfrs.
other: if you use transparent cables [many with wilson sophias do] TA just came out with mm2 tech. the ultra+mm2 SC may also be an excellent upgrade opportunity, depending on your current speaker cable. you may have cable better suited to your entire system synergy and aural preferences. there are many excellent choices for SC.
cheers.
