He added front to back And side to side cabinet bracing.
rebuilt x overs with quality parts, 16 g internal wiring..
also damped woofer frames with led tape and the magnet with some kind of puddy. This does amazing things for the midrange.
I have to say of the 40 or so speakers I have owned these are great sounding and they work great near the back wall. I had Magnepan 1.6 and listened to the Advents 90% of the time. The only negative is if you want something Aesthetically more appealing that sound as good, you will have to spend a good deal of money.
Im considering going to OHM Walsh 4000 or Klipsch Cornwall’s as the also work well near back wall and offer a major cosmetic upgrade but we are looking at 4400.00 or more a pair. I currently have all 4 on EBay located in Florham Park NJ. I’m now reconsidering my decision to part with these.