Alesis USB sound device problems after 10.4.10 update
The simplest solution is probably to downgrade the system.
A reader writes about problems that he and many other users are having with the Alesis iO|2 USB audio device since the 10.4.10 system update. This would presumably fall under the heading of the miscellaneous USB problems we've already noted:
I, like many users have found a major problem since the 10.4.10 software update. Mainly with my audio interface, Alesis io2. I tried following your steps to remedy the input problems and also the downloaded updates, but under the System Settings where you have to select your input device under Default Input, the io2 isn't even in there for an option to click on, nor will it give me the option the mute or unmute... On the Apple forum and discussion page, there are heaps of Alesis users that are having the same frustrating problem: no input options!
It is apparent from the comments on Apple's discussions page that the Alesis device is working for users as an output and MIDI device, but as a sound input device it is not even being seen by the system. The logical hypothesis would be that the trouble lies in the system-level USB drivers. The Alesis device does not require the installation of special drivers; it uses Apple's buit-in drivers. The Alesis Web site says:
The i|o2 [sic: Alesis seems not to have a consistent policy on the spelling of this device's name] is a class-compliant Mac device, meaning that no drivers are necessary for the Mac. Just plug the i|o2 in to your Mac, and it will install automatically.
Thus, since we know that the built-in USB drivers were changed as part of the the 10.4.10 system update, it would follow that these changes have somehow rendered the Alesis device incompatible with the system.
It would be possible, perhaps, to try to isolate the particular USB-related .kext file(s) responsible for the trouble. But, given the poor track record of System 10.4.10 amongst audiophiles in general (such as its penchant for emitting unwanted sporadic audio pops), it seems more advisable to downgrade the system to 10.4.9 in order to restore functionality. We discussed how to reinstall the system and upgrade it to 10.4.9 in various earlier articles.
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