Does anyone do speaker mods?

One important point to remember is that if you put the esotar tweeter and a different woofer in the cabinet of the 140, the crossover has to be completely redesigned. At that point, there is nothing dynaudio about them at all.

There is a difference between upgrading and redesigning. I take upgrading to me matching values of existing components and replacing them with better ones.

There are many avenues for crossover redisign. the forums at HT guide have many members that can do it. In addition, Meniscus audio and madisound do it for a fee.

Speaking as someone who builds speakers, I wouldn't say that removing the crossovers and sending them somewhere is very simple. Especially for those who have never opened up their speakers.

Jsadurni, I disagree that a better tweeter will be more efficient. It is completely driver dependent. Some are efficient, some are not. In addition to needing to potentially pad the tweeter (which is a good point) the crossover point could need to change. Which means complete crossover redesign on the tweeter side assuming it is a parallel crossover. If it is a series crossover, good luck. Some tweeters can cross low, some can not. You would have to know the optimal crossover point and find a driver that met those specifications. No simple task.