What is this?
How to avoid conversion of stereo to mono when feeding analog audio signal from a laptop (unbal TRS out) to a mixing board.
Update: Fixed the issue with the help of a 3.5 mm out to double (stereo) XLR converter. At my most recent workplace, we ordered two of those to be prepared. It works fine - the only drawback is that you need two XLR ins for one signal source, which may be an issue when working with a limited amout of XLR ins (smaller mixing boards).
Whenever possible, I prefer digital communication between devices, as it usually reduces latency while maintaining or improving signal quality. Regarding laptops, the two most common solutions are USB or Dante. For other mixing boards, AES is also a good option.
Imagine the following situation:
There is a spontaneous decision to feed music into a mixing board via a laptop. In this situation, some people do not have a USB interface at hand to route the signal to the mixing board digitally.
What happens instead? They use the headphones out, which classically comes in a TRS configuration - unbalanced L and R out.
Once you feed this into a line in of the mixing board (usually via a 3.5 mm jack to 6.3 mm jack converter), the board combines both channels to mono. I have encountered this exact issue working with an Allen & Heath SQ-16.
As we all know, people can forget adapters... For this reason, it would be nice to have one line in per mixing board for a 3.5 mm jack input from a laptop out. The unbalanced TRS signals would be recognised as two different audio signals. These would then be routed to two separate but paired and (hard)panned audio channels.
