Above all, he wants outstanding top-end extension, transparency, outstanding detail, speed, focus, and great bassI would add, "tonal accuracy". Hardly asking for much, is it:)?
The type of sound described really fits a handful of top-end active pre's. The Adcom may be "on the road" to what is expected -- but, good as it may be, it hardly achieves the targets. At its price point, it really wasn't meant to better, say, a Blowtorch.
Given the requirements, the line level source, and the easy load represented by the Parasound am, my recommend would be a TRANSFORMER volume control. Bent offers these (they also offer a kit, I beleive) at a reasonable price.
The resulting sound should be very close to what you describe. If not, it's due to upstream or downstream elements -- not the trannies.
An idea, anyhow....cheers