http://www.stereophile.com/content/wilson-audio-sophia-series-3-loudspeaker-measurements#Bg6XMa0CYPECFV8F.97
Look at the tests done on these Sophia’s, the last 2 sentences first paragraph, indicates that many amps that have output transformers (tubes and the MC452) or amps with limited current ability, will sag a little current wise in the bass, and because of that will give a brighter presentation to the balance of the speaker.
Look for amps that have good current drive down to 2ohms if you want a more even natural balance, as Wilson would have voiced them. Probably with Krell or D'Agostiono amps or such.
Cheers George
