Hey gang, I have the 975 with 4 devices connected via HDMI, and one cable to the TV. TV is Vizio P75-C1. It did a firmware update a month or so ago, and ever since it can't acquire a "handshake" with the 975. Audio keeps unlocking, and no video to the TV. If I bypass the reciever, all is good. Latest firmware for TV is 3.4.8.5. So far Vizio support hasn't been very helpful. I've told them if they can't find a fix for me I'd like to somehow roll back my firmware. Awaiting a response. Anybody have any thoughts as to what the problem could be?

What vintage is your 975? You can check the SW version of the 975 by pressing Input and Mute buttons together. (DO NOT press Tuner and Mute together as this will perform a factory reset).

SW version 5.3 is the latest that I'm aware of.

I have a Vizio M55 (2015 model), Outlaw 975 --> Vizio basically doesn't work. Vizio --> 975 (via HDMI ARC) works about half the time. Welcome to the world of HDMI handshake problems.

I recently had an electrical incident when hooking up my laptop via HDMI to my older Panasonic Plasma TV. I don't know exactly what happened but I heard a pop and my USB-C to HDMI dongle and HDMI-3 on the Plasma were both fried. Since then I can no longer get a picture from the 975 to the Plasma. Source devices connected directly to the TV work as did the ARC output from the Plasma to the 975. After a lot of effort, I ended up getting a TE HDS-42AVR from Outlaw (which is also an HDMI conditioner per TE). It solved my problems. Of course your results may vary.

So to follow up on this post, I ended up getting the 976 preamp and swapped the 975 out. Plus all new cables rated for 4k. Problem solved.