SENNHEISER GSX 300 vs Sound Blaster X3 (Which to pick HELP)

Looking to buy an external DAC/AMP that supports 7.1 surround and has Sidetone. I love Virtual 7.1 surround and dislike stereo. I know that there's a few surround options on Windows 10 but I dislike them as well so I am down between these 2 DAC/AMP options from the title. I was wondering if anyone owns either of those and could tell me how well the 7.1 sounds and how well the sidetone works.