Interesting. I've had all three versions of Alan's SR17's and currently own the VIII as well. The VIII is certainly the most refined of the lot, and all have been very impressive, coherent speakers, so that is saying alot. I haven't had the same impressions of the upper mids, in either this version, nor any of the previous ones. I have had similar impressions of the speakers not quite living up to their 89db claimed efficiency. I don't know if I'd say they're as low as 85 though. My first thought was break-in, but 500 hours certainly covers that. I biwire as well, but haven't noticed much of a difference. I wonder if you just got yours, whether they are bone stock, or whether Alan incorporated the newer crossover from the V. IV? I've found the best results with the SR17's to come from throwing some power their way. I know they are voiced for tubes, according to Alan, but I've also had great results with at least two SS solutions, currently using a 180wpc Odyssey Dual Mono. If I asked anything of them, it would be to go a bit lower, though I'm still amazed at how low small boxes like these can go. I certainly can't complain about the quality of the bass though. No experience beyond that to convey, except to suggest trying something with more muscle behind them, tube or SS. Perhaps you have a friend with a system with more muscle that you could try them on. Speaker height should allign your ears with the tweeters by conventional wisdom. That will depend on your measurements and the seat you use to listen. My SR17's are on 28" stands.
Marco
Marco