My soundcard (Sennheiser HDVD800) has a 6.35mm jack output that I'd like to adapt to listen on my earphones (3.5mm connector). However, I'd like to retrieve only the first channel (L or R) outputted from the soundcard in both earphones (I am not interested in the other output on this specific output).

Will it work if I use a mono jack adapter (6.35 to 3.5mm) on the stereo output? Will the dropped signal not interfere with the other channel? If no, do you have any suggestions on how to achieve this?

Thank you

2 Answers 2


Mono to mono adapter won't work – you would hear left channel in the left earphone and silence in the right one.

Mono (plug) to stereo (socket) adapter will let you hear left channel in both earphones.

What you describe could be also possibly achieved in software.


Bad news is that you will need a special cable. If you simply connect a mono plug in the stereo headphone output it will shorten the right signal to ground. I would expect the headphone amp to survive that, but it will not like it.

The good news is that you can make or buy a Y cable: stereo to double mono. Each output is one of the channels, L or R, you choose. Example here (note that this is an example, not a recommendation, the Y-cable is not the most common but decently usual in pro sound. Fun fact it is used on analog mixers for effect insert send/return): https://www.thomann.de/se/pro_snake_tpy_2003_jbb.htm

Next you use a 6,35mm to 3,5 adapter, mono or stereo does not matter.

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