Hi, first of all, thank you for your help, both of you! I also learned a lot from this experience.
> e.g. a symbol was leftover in symbols file: > + _ZN8Echonest12AudioSummary12setTimestampEf@Base 2.1.0 > and was preventing amd64 and i386 builds to succeed. You are right, it seems that I have forgotten this line to exclude for the other architecture, sorry. But now it looks good for me, too! The package on mentors.debian.net should be up to date, now. (Hopefully :-)) Stefan