I don't think I would want to go back from having easy to drive speakers. Mine are 98dB, 16 Ohms and flat to 20Hz, using field coil drivers (Classic Audio Loudspeakers T3). When I heard the first version back in the late 1990s, I bought them right away and have yet to hear anything surpass them.
The next eye opener for me was the use of a Distributed Bass Array. The first person to seriously offer any such thing to high end audio was Duke LeJeurne of Audiokinesis, with a sub called the Swarm. Finally a solution for that pesky loss of bass at the listening chair, while the rear of the room would be just fine. So I use a pair of the Swarm subs in my system to break up standing waves. Really effective. If I had it to do over, I'd run four of his subs and the main speakers would be a bit smaller since no need to plumb the bottom octave, but I really don't want to give up that efficiency of the mains. Easy enough, but I already have the best speakers I've heard so I don't expect to make a move.
Finally class D offered something to me sonically a few years back that caused me to sit up and pay attention. I'd thought for years it was a sort of rising star in high end audio, at this point I realized that as a manufacturer, if we didn't get a handle on it we'd get left behind. From a designer's point of view, class D offers some solutions that are very difficult if not downright impossible with conventional amps: getting a really good Gain Bandwidth Product value, something essential if you want to apply feedback to an amplifier properly. We had avoided feedback in our OTLs precisely for this reason; if you don't have enough GBP in your design, the result is usually distortion rising with frequency. If distortion does not rise with frequency, the amp stands a much better chance of sounding like real music. Finally there's something out there that can give you the smoothness thru the mids and highs that you expect of an excellent tube amp without any tradeoffs except overload (which is otherwise instantaneous). Since I'm a tube aficionado, to me this also means that class D is able to take on A and AB solid state amps and still come out on top. The result of that in my own system has been great; no more tube worries, no heat, smaller size and best of all, better sound.