Duke LeJeune (Audiokinesis) knows a lot about Clayton amps. You should ask him.
Or was that ...uhm... let me check here a bit..
I read that on audioasylum some time back, but it seems that it is that he knows Clayton Shaw (Emerald)
Uhm... ok now I'm a bit confused.
But have you tried to ask about this on audioasylum? I think there are a lot more members there with Clayton amps.
And by the way 'Daedalus Audio' used a S40 on RMAF this year, that could mean that they have an opinion on them.
Look for reports online from RMAF 2008, room 1021 - they could contain some info on the sound of the S40.

Imperial