If Clock Control is ON in the PTHD card settings, you will not be able to adjust the H9000 clock source because it is being forced to use the PTHD card as the clock source.

This setting should be used with a Loop Sync configuration. If not use Loop Sync, you should turn Clock Control OFF, and set the H9000 clock source to Word Clock.

Using USB audio will give you an additional 16 channels of audio. You will need to setup an aggregate device and configure the clocking correctly as described in the manual here: https://cdn.eventideaudio.com/manuals/h9000/2.2.11/content/setup/usbsetup.html

You can use USB audio and the PTHD card simultaneously if you need that many channels.

Do you have a specific goal in mind with your setup? Are you looking for a certain amount of channels etc?

The PTHD card will give you 32 channels of I/O, which would be more than enough for many users. If you need more I/O than that, then it can be done, but it seems to me that you are going down many different paths of H9000 configuration options and I’m not sure if this is necessary for you.

Some basic ideas of how you use the H9000 and how you’d like it to work with your setup will help me suggest the best options for you.