Yes to the Logitch G33. (but read my comment).
*You use the optical cable to input up to 7.1 surround into the Mix Amp Pro.
It appears that you can toggle surround ON and OFF via the Dolby button. So that would be converting surround into a STEREO output.
**However you listed a USB headphone. The PRO is meant for 3.5mm, stereo headphones.
The G33 appears to have two inputs, USB and 3.5mm. (why so hard to find the information?)
I guess the DAC (digital to analog converter) is internal to the headphones, or else the computer software manages the conversion which I doubt.
Anyway, on PC you have the option of using USB or 3.5mm. On the PS4 you would connect the 3.5mm cable to the Pro, though again toggling the Dolby surround feature on should be almost identical to using the USB cable and Logitech surround software.
PS4 7.1-> MixAmp Pro-> stereo (surround off)
PS4 7.1-> MixAmp Pro-> 7.1 surround (surround on, which is emulated over stereo headphones)
It does alter the sound NEGATIVELY in some cases, but in others it enhanced things look foot steps. So you can EXPERIMENT to see what's best but I wouldn't leave it on, and probably it's best to use STEREO mode for movies.