This probably a really silly question...

I have a pair of Sound Dynamics 300ti that Harry Pearson liked back in the late 90s. The 300ti is an 89db speaker, 4ohm impedance. My question: is there a way to modify to higher efficiency and bring impedance up to eight ohm? This speaker has a 8" woofer, 5" midrange and 1" or less beryllium tweeter.
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.
I don't know what kind of amp you are looking at, but any decent solid state amp should work OK. I wouldn't fool with the speakers themselves, but if you need to make them an easier load for your amp, an external Autoformer may be just what you are looking for. I know that Speltz (My spelling may be off - The same guy that makes the Anti Cables) makes them and they're not too expensive. I don't know if you can increase the sensitivity but you can probably turn it into an 8 ohm load. It would be worth looking into.
you could try a Speltz Zero autoformer to increase impedance especially if you use a tube amp with them.

fwiw I find my 50 watt NAD to be plenty of power with my 300ti speakers.

let us know how it goes for you

I am really enjoying my pair and would like to hear others thoughts.
Jeffrybehr, I don't really have a problem. Back when I bought the 300ti I drove them with the Music Reference RM10 or Golden Tube SE 40. Now, they are sitting in a closet out of rotation. My current amps are Cary V12, Cary SEI 300B, Primaluna Dialogue One, as well as an Almarro 205MK II. My speakers are Infinity Prelude Compositions, Tekton Lore and Tekton 4.5. I like the sound of the 300ti and I would like to utilize them with lower watt amps, SET.

Philjolet, thanks for the suggestion.
Zd542, I don't have trouble driving them with tube amps as such, just the really low-watt jobs, which I have a hankering to do...and I'm a tube guy all the way, haven't used any SS for ages, last being a Forte 4, NAD 3020, I think, too far back to remember.

Thanks for the Autoformer suggestion.