Mac Mini doesn't "see" Peachtree Grand

I have a Mac Mini, circa 2010, running the latest OS. When I plug the USB cable in between it and the Peachtree Grand Pre X-1, the PT doesn't appear as a device when looking at the audio output options on the Mac. I tried the same cable plugged into my Macbook Pro and the PT shows up there just fine.

Any ideas why the Mini wouldn't recognize it? I tried multiple reboots and power recycles with no luck.
If more than one USB port, try another.

Good Listening

Try a different USB port and see if that helps. Also try using a different USB cable - some custom cables disable the power connection which may prevent the devices from handshaking correctly.

If that doesn't work...

The X-1 shouldn't need a USB driver but the older variants apparently did.

I don't suppose the MacBook Pro had drivers installed previously, did it?
Tried all the ports and I never installed any drivers on the MacBook Pro. I will try another cable.. The initial one was just a cheapo I had lying around from a printer. The X-1 version I have, isn't supposed to need any drivers. Might just have to contact Peachtree on Monday.
did you manage to get it to work?
So going back and forth with the Peachtree Audio guys (very helpful BTW) they determined there was a current leak across the USB ports between the Mini and the Grand. If I used my Apple Cinema monitor, which has a grounded plug as well as needing one of the USB ports to function, the problem went away. It also was able to be resolved by running a 3.5mm to RCA cable between the Mini and the Grand. So it comes down to a grounding issue. They offered to do a simple mod for free to resolve it permanently. Or I could just keep the 3.5mm to RCA in place....but that ties up an input on the Grand.

Haven't decided what to do yet. But good to find out there are a couple of possible solutions.
You might want to try the USB-X. I think it allows you to change the way the Earth is connected on the USB power lines. You might want to use the same distributor as the preamp