Having owned virtually every ML speaker during the time frame you've owned the SL3's, 1995-present, I'd suggest you're so accustomed to the ML signature sound it's tough leaving ML and finding pleasing performance in a traditional 3 way design. I've tried it for years, and the closest I've come to that lush electrostatic heaven was delivered via a single driver design matched to a small 300 B SET amp.
I'd heartily 2nd the earlier suggestion of moving on to newer Logans. Vista's, Vantages, and Summits will bring you a fresh performance and be a step up from the SL3's.
To those who've not experienced integrated bass with ML's that's never been an issue with my CLS's, Requests, or SL3's. Any decent sub properly dialed in at the right crossover point has never had me longing for something different from a traditional speaker design...in fact the trade off to be had by leaving the ML sound completely is too large a trade off, for as I suggested, once electrostatic never back...although I always have several different types of speakers and amplifiers on hand, therefore I choose not to have to live without them...bottom line, once that lush midrange is in your ears it's an uphill battle for a traditional speaker to compete with...but certainly if one has enough money they can in theory perhaps find something better...but at the price point for a pair of SL3's upgraded w/fresh new panels, or used Vantages commonly found now at $2500, I don't personally know of anything that will deliver the sonic goods at that price point that will be nearly as satisfying.
