I picked up a used Premier 17LS last spring and love it. I would say it is not dark sounding at all with Maggie 3.6's and a Bryston 4BSST. Lots of shimmer, detail, wide soundstage with good depth. I think that room size, and speaker placement constraints have the most effects on soundstage parameters. Also, I would define a laid back sound as a sound quality being relaxed, warm and less detailed. Probably not synonymous with a deep soundstage. All in all a very nice preamp.
