I also tested the audio recording of the ISDV2.4 in a quiet room environment.
After importing this recording into my other Windows NLE, Corel's Ulead MediaStudio Pro 8, I examined the waveform in that program's "Audio Editor," which provides a full-screen waveform view.
The visual representation of the waveform reveals a lot.
The audio is not normalized.
The peaks and valleys of the waveform extend only halfway from the center line.
When I normalize this audio, the peaks and valleys extend all the way out from the center line.
And it sounds much better.
I'm going to do the same test with the Sanyo VPC-CG6.