PieroMuroI wouldn't worry about missing the HD6XX. For your next headphone purchase with gaming in mind, I recommend these models:
Beyerdynamic DT 770 Pro 80 (excellent sound-stage for a closed-back headphone, tight bass response)
Beyerdynamic DT 990 Premium 600-Ohm https://www.amazon.com/dp/B074KJS1G3
Sennheiser HD598 SR / HD579
AKG K702, K712, or K7XX (available on Massdrop)
Lasmex L-85 ... if you're willing to EQ and Brainwavz-pad-swap them (See my customized profile on the Lasmex page.) The V-MODA BoomPro gaming mic can easily integrate with this headphone.
Were you planning on plugging-in the headphones directly to your computer? For better sound quality (and louder maximum volume), you will need to get a DAC/amp. iFi has some superb units.
eeldivadFor the HD6XX, I would recommend a higher-quality, more-powerful DAC/amp than any unit from Micca. The iFi Micro iDSD Black Label is vastly superior in every way - most significantly in sound quality.