I REALLY APOLOGIZE for not seeing this email sooner! I've got to get the email notifications working...
Hmm. I'm seeing the same behavior. I know it used to work, because the TPA81 I'm using to test it has an address of 214 (0xD6), which I changed w/ the i2cp command.
I'll find out and let you know asap. I'll also fix the email notifications this coming weekend.
I just fired up a Serializer w/ the TPA81 I was using a few days back, to try to debug this problem, and it seems that the address change did work from before.
Furthermore, I tested it about 10 times tonight, and it worked every time. So, it looks like the command works. However, it may take a power cycle for the TPA81 once the address is changed for it to start recognizing it? During the testing tonight, it started using the new address right after I changed it. So, it's not the norm for a TPA81 to require a power cycle, but why don't you try it, and let me know.