Well, here is the latest on the great experiment with the Parasound A21.
At 11 o'clock on the preamp while playing Fleetwood Mac "Rumors", the A21 one started to clip and went into protection mode.
I routinely run the W4S ST1000 at 2 o'clock with no problem.
The answer is 400 watts into 4 ohms is not going to cut it with the Thiel CS 5i's.
Any other suggestions beside the Parasound JC1's?
Dsper