Seems like an honest mistake on the part of Slimfoot. And based upon the wording on the site and the images many likely fell into that trap. I believe this is what the original model said relating to this based upon the 8D:

"Gain Controls
The...offers gain adjustments for each channel pair, allowing you to independently trim output levels in each zone. In volume control-based systems, these may be used to prevent harmful clipping that could cause damage to the amplifier or speakers.

Global and Individual Available Inputs
It is single-source capable but also showcases unique room-specific capability. Whether the system needs to play the same thing everywhere or each zone needs its own source, it can easily be done with global or direct-line inputs."

I've never run across an amp that would not allow individual zone gain adjustment when using the global input bus. Based on the info above I would have (if that was a SKU I was interested in) ordered that amp and would be just as upset. I'm sure he can send them back for the "A" version....shouldn't it be "B" ?