Building a stereo/mono switch box

[denti alligator]

If you have one of our amps or preamps, the way to do it is in the balance switch or in our attenuator upgrade.

Can you explain how and maybe also say how it would be better than making a switch as Joshua describes it in this thread. Thanks.

[Paul Birkeland]

You can add a switch to connect the middle lug on each level of the balance pot together and that will give you a mono signal and your source components won't have their outputs shorted together in the process. Whether or not this matters is certainly up for debate, but it can't hurt anything.                                 

[Adrian]

Just checking for understanding here.
Currently I use two tonearms, one with a stereo cart for stereo and one with a mono cart for monaural recorded albums.
Swapping out the tonearms is easy and takes about two minutes.

Is there any other benefit to using a stereo cart on a mono recorded album going through a mono switch configuration compared to using a dedicated mono cart (other than having only one cart for both stereo and mono)?  Any downside?