Sorry, I posted something close to this today and then saw yours sounds like my issue.

If you turn the treble down does the distortion sound go away? (sort of) Mine seems to be connected to the treble some how. I hate to double post but now that I see someone has sim issue here this is my problem, sound like yours?

Well I had the installed XM but really wanted Sirius. I made a deal with the dealer and am having issues with Sirius. The Sirus radio is a factory Toyota reciever along with HU. No FM Mod.

Issue #1
When I had XM hooked up to my Toyota Camry I swear it scrolled the letters so you could read all of the text. Now that I got Sirius it only shows 10 letters and I can't read 800 numbers or full names. It's a Toyota factor Sirus reciver that directly connects to the head unit and is not connected by FM Mod.

Issue #2
When the treble is turned up I get distortion. Crackles or sounds like distortion when someone talks, a vibration of the voice like the speakers is blown or vibrating and only when Serius is on, AM and FM are fine along with a CD. Once I turn the treble to -1 to -5 it goes away but once I turn the treble up is when I have the problem. I messed with it today, it's like the treble setting in the sirus reciver is set to high so when the treble is turned up it vibrates or distorts. I didn't have this problem with XM.

I have had the dealer check all the connections and had Sirus send another signal to my radio, no luck.