Interesting that the Sound Dynamics 300Tis still get discussed--and KEPT! I bought 2 pairs, one brand-new in 1994 as part of the last batch (of 50 pairs, I believe) that Audio Products International put together as a result of the publicity HP and TAS generated, and the 2nd pair, used and for a pittance. Currently both pairs are on long-term loan to my 2 adult children who love them.
I believe there's no way to increase the sensitivity or impedance without a complete redesign--new crossover AND bass and MR drivers and maybe tweeter too--and then they'd be different speakers. :-(
These were and still are great-sounding speakers for their price; what problem are you trying to solve?
BTW, decades ago, I talked to Ian Paisley, the designer, about these speakers and their crossover. Altho he felt the 300 was the best version--the sweet spot--in this series of TITANIUM-dome-tweeter speakers, I often fantasize about just how good the dual-8"-woofer floor-stander might sound, but I've never even seen a pair.
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