When loading a GPO instrument in Cubase I assign it to a midi channel but also get another (VST ?) channel in the mixer relating to it.
The midi channels don't seem to control the instrument volume so I am assumimg that is done via the second channel. At the moment all the instruments seem to go through only one of these second channels.
How do I assign them a channel each so I can control their individual volume?
(Sorry it's a such a newbie question but I have searched for simple instructions without any luck).
The best thing to do is to go to the tutorials page and go through the appropriate tutorial.
In brief, when you add a GPO instance to Cubase, a VST (audio) entry is created in the mixer. This handles the output of the GPO instance.
(BTW, the GPO player can have up to 8 pairs of outputs. The default is 1/2, which is what the the one VST entry is set up for. You can create additional VST tracks in the mixer to receive on the other outputs of the player instance. If you're just getting started, stick to the simple configuration--outputs 1/2--until you get the hang of it.)
The input to the GPO instance is via its 16 possible midi channels. You'll notice when you load an instrument, for example into slot #1, that its input midi channel is "1" by default, slot #2 is "2" by default, etc. You would route your sequencer's midi track to a GPO instance and, within that instance, to the appropriate midi channel, which corresponds to a slot/instrument. Each GPO instance has 16 input midi tracks. If you are using multiple GPO instances, there are 16 per instance.
Many GPO users do not modify the default volume settings of the GPO player. The "volume" (more than volume, really. It changes timbre also) of the GPO instrument is by default controlled by the mod wheel.
If you really do intend to control/modify the default GPO player volume and pan settings from the sequencer, you need to click the "Options" button on the GPO player (below the "LOAD" button) and turn on the "Use Standard CC#7 / CC#10 Volume and Pan Settings" option.