I am finding that Ardour’s support for multichannel plugins is mixed. In v9, I have some VST3 multichannel plugins that instantiate as multiple-stereo instead of 16x16, while the AU versions do not allow more than 2 input pins. This type of plugin provides a GUI based on what the host workstation can accommodate, and Ardour’s multichannel support is not accurately indicated when I use these particular plugins. Oddly, if I return to some previous versions of these plugins, the 16-ch nature is supported. These particular plugins are reverbs from LiquidSonics on MacOS, and do work as expected in other apps.
One of the great things I like about Ardour vs MixBus is that Ardour does not obfuscate multichannel support. I would certainly like to see this continue.
h