Proac Ribbon Tweeters Damaged

... once I get these repaired, I will have to decide whether I feel comfortable continuing to use that amp, or bite the bullet and purchase something new.

Based on what has been said in the thread thus far, if in fact electronics in the system caused the tweeters to fail I'm not sure that the amp is any more likely to have been the culprit than the CD player.

Good luck as you proceed.  Regards,
-- Al 

Regarding the possibility that the root cause of the problem may have been the speakers themselves, here are some excerpts from the following thread, although it is about a different Proac model:

https://forum.audiogon.com/discussions/proac-problem-tweeters-or-crossover

Audioconnection 3-10-2015

Having sold Proacs for 24 years
It could be a simple fix.
Unscrew and remove both top tweeter section knurled binding post nobs.
Insert carefully a small blade screwdriver into the hole and gently tighten the top binding posts clockwise a half turn till snug if its still loose go for another half turn but do not over tighten.
If this seems to get back your volume you are set.
If its still intermittent removing the woofer and get into the crossover board connection area and clean up the star washer x over board area where the binding posts meets the board will complete this.
Hope this works for you
JohnnyR

PBNAudio 3-16-2015

Jonny R from audio connection gives some good advise on terminals however don’t tighten them from the outside, open them up and tighten the nuts on the inside. Proac use Mitchell binding posts they have a knurled shaft you don’t want to loose the grip they have in the mdf plate that they are mounted in.

CTSooner 3-17-2015

PNB, that’s also great advice. I have had to do that with a few different Proacs that either I owned or my friends have owned. Wish that was fixed by them in the 90’s when they first encountered the problem.

Perhaps over time internal vibrations have caused a connection to loosen. And if that occurred at slightly different times in the two speakers, is it possible that it wasn’t noticed until the tweeters in both speakers stopped working?

Hope that helps. Regards,
-- Al

Another possibility, in addition to those that have been mentioned (especially the possibility of an ultrasonic oscillation), is that a fault in the amp is causing a large but very brief transient at turnoff. (I assume, btw, that you are turning the components on and off in the proper sequence -- amp on last and off first).

I once had a high powered solid state amp, in that case a Threshold S-300, which developed a problem that caused it to put out what seemed like nearly a full power transient for a fraction of a second, about 20 or 30 seconds or so after it was turned off. In that case the transient was clearly audible, and produced visible movement of the woofers, but if such a transient is brief enough it might not be audible and might have sufficient high frequency content (corresponding to the rapid change in amplitude) to damage tweeters.

Also, what preamp and what phono stage are you using?

Regards,
-- Al