Also with regards to your gain question I realized I didn't fully answer it. The signal chain was Sony Sound Forge, playing FLAC or MP3 files with no additional processing out via ASIO to the Scarlett Mixcontrol. All digital levels were set to unity, output was set to DAW1 and DAW2, bypassing the mixer. Scepters were plugged in to line outs 1 and 2 and level controlled using the analogue control on the front, input gain on the Sceptres was at the lowest setting. The S/PDIF out of the Scarlett is wired to my Denon receiver, its internal preamplifer controlled the line outputs to a Rotel amp, which hooks to the SVS speakers. I balanced the levels at 80dBSPL for the first tests and then 75dBSPL later (I don't like loud music) using pink noise measured with a Checkmate CM-140, verified against the set level on the receiver which is reference calibrated (0dB = 105dB SPL at the listening position). I switched back and forth by muting the monitor outs in mix control, and muting the receiver outs.
 
As I said, hiss was present in the Sceptres whenever they had power. Not loud, but audible. There was no hiss (well no audible hiss, if you press your ear near the tweeter you can hear some) in the SVS speakers at any time.
 
I don't think I screwed any part of my testing up.
 
Also with regards to processing/room correction the SVS speakers are corrected with Audyssey MultEQ, a low resolution version of the algorithm in ARC. I tested the Sceptres at different settings on their internal controls, finding I liked them better with the highs tamed a bit, as I do with the SVS speakers (I run them with the Audyessy curve in this room normally, which lowers the highs, in my old room I left them on the flat curve) the room has too much HF reflection I think.