Mystery solved. The echo was added by the amp, in the "AUTO" mode. When switching to "Source Direct" or "Pure Direct" the dialogs suddenly became clear. Apparently this (old) Audyssey is having an issue with phantom center channels and somehow JAMOs are less forgiving (or more revealing, more affected by that, you name it) than the ELACs probably because their stage is naturally wider and the sound is more in front of me rather than in the speaker.
I have also realized (after reading amirs article) that I have done it all wrong and I need to listen to the speakers in mono.
When re-listening to some classical tracks (in mono), the triangle hits indeed sounded like bells on the JAMOs whereas the ELACs told me there was a triangle hit, but no tingling followed.
Funny thing is, I have realized that over the past days, no matter which speaker have I decided on as being better, I felt sad for the other paid. Either because
- I felt like I have been listening to a wrong pair of speakers for the past years and I need to get rid of them. Together with the doubt of what If they are indeed not that wrong and I am just unable to properly reveal their true quality and would be 'throwing out' an exceptional pair of speakers.
- or that the ELACs are not that big of a difference (or even a let-down) to my current speakers and I can't increase the sound quality being on the budget I am
Anyway, I have learned a lot from this experience, thanks for being here and helping me.