If you want to connect a stereo channel pair from one block to another quickly - you can simply do the following
- Hold down the SHIFT key and then DRAG the block you are making a connection from to the block you want to make a connection to
- Align the pins approximately so that they are touching.
- Let go of the SHIFT key and move the block you dragged over back to where you want it.
A stereo connection should be created now.
Here is a 40 sec video