This subject was discussed last year and my take on the subject is:

1-After taking 2 wires from the from the back of my keyboard (Stereo) into a “Y” connection; two wires coming into one and putting the “Y” connection into the Bose Compact I heard no separation or panning right and left. From the Bose.

2-For me the Bose offers enough to compensate for the loss of panning.

3-If you have programmed panning into your style/song be sure to use a “Y” connector.

Although the outputs of the keyboard state; Right and left; and the Left gives you Mono a combined left and right I would give the “Y” connector a try.

My personal opinion is that if you have a stereo set up and you stand 20 feet from the speakers or even 10m feet you will not hears a notable difference. There are many other areas where you can improve your sound; and the difference can be heard.

Only my opinion, John C.