How did I know my panels were on their way out?
One of my channels started to fade (wouldn't get as loud as the other side.) I did a bunch of A/B testing, including swapping the electronics panels from the back of the woofer cabinets from one speaker to the other, and I eventually determined for sure that one of my panels was more muted than the other. In the following weeks, the more muted panel actually stopped producing sound on its bottom almost 8 inches (the low mids).
While doing this analysis, I reached out to Martin Logan about replacement panels. The replacements are not only more than $1,500 for the pair but Martin Logan was also at least a few months out on getting new panels to me. All that cost and waiting, and the idea of restoring my 25ish year old speakers... I elected to plunk down $4K on a pair of ESL X speakers.
I did not realize how far my SL 3 panels had declined until I put the ESL Xs into my system. In the end, I had in fact been pumping the aging SL3s with a shitton of Class D power amplification (and they sounded OK until they started to wilt). When I put the brand new ESL X speakers in the system, the Class D mono blocks were suddenly plenty powerful but entirely too harsh for listening at medium or high volume. I then realized that the SL3s hand probably been losing their edge/nuance/detail for a while.
Needless to say, the set of ensuing changes came at a significant cost (new power amp, interconnect changes, etc), but today the ESL X speakers are performing wonderfully in my evolving system.
I wish the 25ish year old speakers were not seemingly destined (at some point) for a landfill. Wouldn't it be cool if there was something like a trade-in or recycling mentality with these items? Imagine if Martin Logan gave purchasers of new speakers some percentage off a brand new pair (15 percent?) if they handed over an aging pair? Like we pay 85 percent of retail for a new pair and they take away the old ones when the new ones are delivered... I might have gone up to ESL 9s if such an incentive was in play.