I thought to begin with the OSS and NetBSD drivers since I am most familiar with these. The intention was to integrate these drivers in such a way that it will be easier (although probably not trivial) to then bring the other drivers in.
Although short sighted, I intended to first consider the differences in OSS and NetBSD audio drivers and then see what is needed to support other drivers once I have successful integration of these two.
Of course, I am thankful for all the comments so far and hope I am skilled enough to satisfy everyone :-).
Any such solution needs to take into account all the drivers; we don't want a mechanism that will only work for a specific case, it will make things an even bigger mess.
Kind regards,