High Impedance Headphone Jack (MacBook Pro 2021) - Is there a way to Manually increase the voltage output for headphones with low impedance, but need higher RMS?

You can’t… the Apple DAC/AMP will do that automatically…

Why would you like to increase the voltage on low impedance headphones? Anything under 50 Ohms, you might fry the coil, or cause other damage…more power doesn’t mean better sound…

read more here:

https://support.apple.com/en-us/HT212856

The DAC / AMP in the MacBook Pro is not really meant for ‘professional use’… it is only meant to be there in an emergency case scenario. I still use an external DAC/AMP for all my video / audio editing (with 250 and 600 Ohms headphones)…

Your AKGs require a DAC / AMP that has a “power match” feature. So, the DAC/ AMP will test the headphones and match it with the adequate power level…Most external units will do this…

The only thing you can do is crank up the volume…if needed… on the MacBook Pro