Before I start, I want to point some things:
I bought this cans from user bruma on the forum, and I want to thank him for the deal, the almost-paranoic packaging used to send the cans and all the useful info he has provided me.
Also, he made some restoration on this cans, so this impressions can not be true for an untouched ET1000.
Last thing I want to point is that I'm not a native english speaker, nor do I have a formal training in the language, and I'm bad at describing how stuff sounds even in my mother languages. So this is more a shy attempt to leave some information reflected for future reference -as I could find almost no info on this cans before buying them- than anything else.
The quick sumary on how they sound is that bass is less strong than in my DT770 -only other pair of "serious" headphones I have to compair-, but it is clean and well defined, and all the other frequencies sounds great, everything is well separated and nothing prevails, but it is not sounding flat, cold or excesively analytic. There is a grainy quality in the sound, but nothing big or disturbing, at least for me.
They perform well with all music I have put on them, but they seems a perfect match for jazz and classical.
Worst point for this headphone is that they are unconfortable when used on long periods. Some user on the forum comented on using some Sony pads on them: I will try them and update this review as soon as I receive them.