I purchased this unit from Costco, and it is a re-branded unit that is actually an EXTREMELY close cousin of the KDL-46Z4100.
I have lived with over a year of audio dropouts, as I'd switch to my HTPC and it'd just not "sync up" and I'd not get audio and have to shut down the TV and sometimes even shut down, or disconnect the HTPC!
The device attached to it (ATI-6800 series video card with every new software avail! for the last year and a half) PC itself, and need to re-sync to get the audio working.
This BUG drove me CRAZY!!!
This was a MAJOR BUG!
The Sony support site has NOT acknowledged this unit to have any new firmware with the built in Ethernet support upgrade option, nor the web site will acknowledge that the Costco branded version is capable of this update!!!!
I read here that this unit is a re-badged "KDL-46Z4100"
The firmware I had before the USB upgrade stick was inserted was "HO-F-QN-B-CO"
I downloaded the firmware for the PROPER name of the set:
This is S/W version "version 2.06r" and I have no way of telling the original firmware other than the contact Sony page with the "HO-X-XX-X-XX" shown.
I formatted the stick fat32, and powered down the unit, and when I powered it up with the downloaded firmware on a simple 8 gig stick, formatted fat 32, it went into a flash cycle with LED's blinking colors on the front pannel I didn't know existed!
It downloaded and rebooted and installed the new firmware and I ended up with:
"HO-F-QN-B-CR" and the Audio issues are GONE!!!!
So I can state with a FACT that you can take a Costco purchased KDL-46VL160 and use the firmware for the "KDL-46Z4100" and update it to correct this critical flaw!
I entered the actual correct Serial # for this re-badged Costco set at the Sony web site (82006xx)
When I applied the upgraded firmware for the PROPER branded version of the same set, the KDL46Z4100, It fully corrected the audio HDMI issues!!
P.S. I have TWO of the sets, and I was prepared to use a JTAG and re flash the bricked TV if things went wrong, so I didn't go into this blindly, and now everyone else can do it with no worries!!