Original poster update: As an experiment I brought my office speakers home (Focal 706V - I like them for casual listening) to compare them to the floor standing Triton 7s. Well, I think the problem is solved with the Triton 7s - either they are defective or they just cause far too many room reflections to be listenable. The Focals are so much cleaner and more transparent. The sibilance is no longer an issue, and I can make out lyrics that were obscured on the Tritons. The Focals have a bottom end rating of 55hz, and it's more than enough in my room. I don't think the Focals are world beaters - they don't resolve as much detail or have quite the warmth that I'd like, but there is no comparison between them and the Tritons. Frankly, I was shocked - I know they Tritons are well respected, and I don't mean to criticize them. Since I bought them used, I may very well have gotten one with some problems. Or, it just may be my room. In any event, I'm no longer concerned about the "lack" of bass with a bookshelf. Now, I just need to decide which one to buy
Thanks again for all your input.
Scott