Hello,

I recently purchased an additional pair of studio headphones for a specific reason and it is now my intention to make improvements to my current configuration.

The dual port of my Audient iD4 audio interface permits simultaneous connection of two headphones. Consequently, I am able to drive both my HD600 and MDR-M1 headphones concurrently. However, maintaining consistent volume levels is challenging due to the interface's single volume control knob. It would be beneficial to have the ability to adjust the volume on each headphone independently (leveling to monitoring). While the current interface is highly satisfactory, it is not ideal to replace it.

I am considering the optimal solution, which may involve integrating either a headphone distribution unit or passive inline volume controllers into my setup.

Amps and distribution units
There is a wide range of multi-channel amps on the market, but I am looking for one that will drive my HD600, which has an impedance of 300 ohms and MDR-M1 (50 ohm). This specification makes such amplifiers more expensive. Additionally, more sophisticated devices such as distribution units support at least 6 channels, usually 8, which is excessive in my case.

Passive volume controllers (in-line)
This solution appears to be reasonable, given that my interface is capable of driving Sennheiser and Sony headphones and I require only volume control. I have identified several inexpensive potentiometer-based options, but they are all manufactured in China and, based on reviews, may not be durable. Additionally, some of the models are constructed using a potentiometer with an average resistance of 50k ohms, which seems questionable (50 kiloohms sounds slighty higher than necessary, but not sure).

I am currently uncertain as to the optimal course of action. Purchasing low-cost volume controllers may result in financial savings, but this could potentially lead to disappointment due to the variable quality of such devices. Conversely, investing in an amp when my interface is already capable of performing the same function may be deemed an irrational decision.

I would be very grateful for any suggestions or advice you could offer on this matter.