As Apple revealed in a description for a session at WWDC, OS X 10.5 includes enhanced USB and FireWire audio support. Some of that functionality is already arriving in the 10.4.10 update, which incorporates the FireWire SDK 24 and FireWire 2.1. (The SDK also includes “most” of the source for Leopard’s upcoming FireWire stack.)
You probably don’t care about that unless you’re a developer.
You probably do care that the 10.4.10 update can cause some FireWire audio devices to cease normal function, including the Behringer FCA-202 and Mackie Onyx Satellite. MacFixIt has the full details, and a workaround from Mackie:
Basically, you can roll back the FireWire driver itself while leaving 10.4.10 in place. Of course, if you haven’t yet installed 10.4.10 and you own an affected interface, you might just leave well enough alone for now.
The “glass half full” way of looking at this would be to presume the full 10.5 update may not cause any earth-shaking driver issues, beyond a few fixes here and there. And we may have jumped over some of those issues before the full 10.5 issue hits. My Focusrite Saffire, for instance, is performing just fine under 10.4.10 on two machines. For anyone complaining about Vista, this is further proof that OS updates will generally cause issues with audio hardware, simply because, aside from class-compliant devices, most pro audio gear interacts with the operating system at a pretty low level. Low-level functionality just tends to break first. The question is, can you fix it, and how fast? (In this case, “pretty durn” fast seems to apply.)
Apple still releases more incremental updates compared to Microsoft’s fewer, larger updates, and Microsoft’s changes in Vista were more sweeping changes to the underlying driver model, compared to Apple’s incremental improvements to audio-specific features. The jury is still out on which is better; it’s still unclear to me, for instance, how much benefit the Vista driver model switch will have in the longer haul.