You say it sounds good in headphones, are the phones plugged into the ZED or the computer?
Do you have the USB turned on on channel 11-12?
Is it routed thru channel 11-12 or directly to the main LR out?
Those switches are below the USB gain knob.
How does it sound on the main outputs of the ZED?
The Rec out on a ZED is an extension of the main outs.
What mode do you have the ZED ALT out set to?
With headphones plugged into the ZED and then you PFL the USB channle/ 11-12
what does it sound like in the phones then?
I have a ZED and it’s a very handy compact mixer.