Both speakers want 150W plus in a medium sized or larger room. Use a warmish amp like the Plinius 8200 and warmish cables like Cardas and the Thiel 1.5 is not at all harsh. Can't comment on the 1.6. The Proac 1.5 needs a bit more open accompaniments to get them to be lively.
Personally I find the Thiel 1.5 to be very musically engaging, more so than the Thiel 2.3.
Personally I find the Thiel 1.5 to be very musically engaging, more so than the Thiel 2.3.