I just picked up a USA-SPEC for the Taco, and started reading through the manual this morning. One of the last pages of the manual states that you should not update your iPod Classic firmware beyond version 1.1, or the USA-SPEC will not function in Hybrid mode.
Of course, I took a look at my iPod, and it's already version 1.3. I haven't installed the adapter yet, but I'm assuming I'll have the issue. I had planned on using the adapter in Hybrid mode.
Has anyone run into this problem? If so, is there any way to bring my iPod back to firmware version 1.1?