I use two Sennheiser 906 dynamic microphones to record my 80 bass accordion, one on the right and the other on the left side.
initially I used two independent cables, one from each microphone, to go into two channels of the mixer.
But since the two mics are identical and I ndon't need to adjust their relative volume indipendently, I decided to just merge the two signals and go into the mixer with just one channel.
like all my other constructions dedicated to live playing, this one too must be very practical, very robust, and as essential as possible.

I searched around and I found that for my specific need would suffice an Y cable with some strategically positioned resistors...