I replaced the tweeters on all three speakers and now I can hear what I was missing - the air is back, the shimmering of the cymbals- two tracks that I found the most obvious differences - The Eagles Hotel California and Queen Bicycle Race - The Edge/Growl is there on guitars also.
The speakers sounded good without the new tweeters, I just figured they were voiced to be subtle on the top - live and learn ...
I'd recommend the tweeters refreshed on any ferrofluid tweeter over ten years old.
The I think the DSP33 tweeters are the same as the DSP420s - (see my thread on them)
It makes me very happy to have new speakers.