Please mark alsa-base as Multi-Arch: foreign
Marking alsa-base as M-A: foreign will allow i386 packages that depend on alsa-base to install on a amd64 system. Since alsa interfaces are architecture independent, foreign seems like the correct marking.
$ sudo apt-get install my-32-bit-app
my-32-bit-app:i386 : PreDepends: alsa-base:i386 but it is not installable
Install a 32-bit package that depends or pre-depends on alsa-base and have it properly install.
Minimal as this change on affects multi-arch status only.
|tags:||added: precise quantal raring|
added: verification-needed-precise verification-needed-quantal