Somewhere in the mix, I guess I got lost understanding what code you are looking for.

Have you looked at the protocol sheet?

[Link: awe-europe.com]

The code you want does not exist.

You can turn up/down SUB1 and SUB2 discretely, like you can turn up/down the level of any other speaker discretely. Most receivers have a function in the menu for levels of each speaker; this receiver happens to have discrete codes for each one.

However, just like there isn't a code to turn up/down the FL/FR levels at the same time, there isn't a code to turn up/down the two subs at the same time.

These are levels that are meant to be set one time, either with a calibration microphone, by an SPL meter, or by someone who can do it by ear. You set the level, then you turn all the speakers up/down with the master volume.

I'm not going to tell you how to control your gear or how to do an installation, but I can assure you that the sub (or any other channel) level was not meant as a volume control (or volume limiter). If you are using it this way, great, but that is not the design. In fact, this is why basically every sub on the market has its own v/c somewhere on the unit. You set the level gain, then you control all speakers together. This is how you keep things uniform and even so that one speaker doesn't over power the other.

Maybe you have a soundtrack or music that you want a little more/less bass. Walk over to the sub and adjust the knob accordingly. If that isn't going to work for you, then find a sub you can control through IR or RS232. I assure you, they exist.

If you absolutely want to use the Sub Level +/- in the receiver as a volume control and want it to control both subs, then buy a male/2-female y-splitter and split the signal to the subs. If you somehow think that this is going to limit your preamp signal (more than your on the fly level conversion is already doing, assuming your receiver is even driving more than a couple volts at full volume), then buy a line output converter and ramp up the output voltage of your sub output preamp, split it, send it to both subs, then use your IR code to control both. Though I can't imagine a situation where this would be necessary. Maybe if you were driving high end speakers/sub and needed that extra preamp voltage, but to be honest, if that is the case, get a better receiver than the x series you can pick up for sub ~$1200 on Crutchfield or Amazon. (I'm not knocking the receiver, but I am being realistic about its abilities. Plus, if I were billing by the hour for code search and support.....)

If this whole thing sounds convoluted and like a terrible idea, it's because it is not a great one. It is a solution for what you want to do with your system, which I am having a lot of trouble wrapping my head around.

The only other reason I could imagine you are doing this is some type of night mode function where you want to tone down the subs when watching late at night. There is not a specific night mode, but there are plenty of sound fields or codes for dynamic range control and etc. Good luck with whatever you decide.

In terms of hex, what you want doesn't exist.