X7 has the TPA6120A2, your onboard has the OPA1622. The OPA1622 has actually half the output impedance (7ohm vs. 13 ohm open-loop), which is better.
The 6120A2 seems to have more output current. But that 1622 you're still talking 140mA.
To be perfectly frank, i'd doubt you'll be able to tell them apart in a blind test. And the onboard is actually better suited for lower impedance cans (as low as 7*8=>54ohms, compared to 13*8=>104ohm).