You are liable to get quite a few suggestions here, but I will give you a quick list of ones that I have heard with Harbeth in general, but not necessarily with just 30.1's, as each model does have some differences.
Croft Acoustics-hybrid, Leben-tube, Line Magnetic-tube, Exposure-ss, LFD-ss, Sonneteer-ss, Naim-ss.
Just a start on the amplification side, and some of these also sell CD players and DAC's that work well too. Hopefully you can listen to what you are interested in along with the Harbeths prior to buying! Have fun and enjoy the trip, most of all, enjoy the music.
PS-agree with post above on the modern area.