But I would like to add that although the Sig IIs sound good with my Line Magnetic tube amp, they sound much better with my solid state Parasound A21. I suspect if one has a higher powered tube amp with much more current they will appreciate the power to sound their best.
Again the speakers really do sound good with a wide range of power amps, but I think to get that extra smooth timbre and range, to extract the natural sweetness out of them.....the more current the better.