It's not as important to me as the stereo link for the 525's. I figured if it was an easy thing it would be nice to have the option (especially in the absence of a fader).
I ordered a blank panel to install the compressor link switch and figured this would be the time to implement the gain switch...but I'm sold...it's not that important.
Many thanks for the info..I love API gear, but there's scant info on their modules. Web search for "API 525" (for example) only gets you the same text from the "brochure" again and again on different websites.
Someone here's looking for a pinout diagram on a 225 and for some reason it's not on the API website, although the info for the 500 series stuff is.