124FX has 1/4" balanced out.
Snake is XLR only.
Should I use 1/4"-F to XLR-M adapter or should I use 1/4"-F to XLR-M transformer to send signal to L1 Classic ? I would like to send to Ch 1 or Ch 2 in order to use presets.

Hello Jerrold

Welcome to the forum!
In your case you can use balanced cables all around. You would use an adapter or short cable that is female xlr to male balanced 1/4 inch. This would be used to connect to the mixers main outputs to the snakes cable end that should be male xlr. Now you would use a regular xlr cable to go from the box end of the snake to channel 1 and 2 on the L1.

Let us know if you have any more questions, and thanks for your post.