The sound only comes out of one side...

Hello,

Turntables do not use the same inputs on the back of amplifiers as a CD player, for example.

It is usually the "Phono" input...

DIN input PU magnetic "td"

It is also possible that the cartridge on one side of the tonearm is faulty.

By switching the left and right inputs, we can determine which one is not working.

No one has any ideas anymore??

It's hard to understand your text... and where what you're talking about is located...

Because you refer to everything as "ENTRANCE" while there are inputs and outputs... for example, the wires from your board are outputs that you plug into the inputs of your amp, etc...

I still understood 50% and guessed part of the rest, but not with certainty.

-- You have an issue with the wiring or shielding... you have one amp with connected grounds and the other with separate grounds, for example... but that can't be guessed on a forum... you need to have the device in hand, take continuity and isolation measurements with an ohmmeter, and take action to correct it.

-- Is the cartridge of the turntable properly stereo and not mono??

I suggested you reverse the outputs of your player with the inputs of your amp... how’s that working out..?

-- Don’t think that everything is working correctly. The proof is that you’re here because of a problem...

-- You can put a wire connecting the ground of the left channel with the ground of the right channel, either on the outputs of your player or on the inputs of your amp... when the player is connected.