Is it possible to use a DPDT switch to swap 2 inputs and 2 outputs?
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Implementation using a 4-pole 2-way switch.



Figure 2. The 12-way rotary switches such as those made by Lorlin are available in 2-pole, 3-pole, 4-pole and 6-pole versions. A tabbed washer under the lock-nut limits the number of switch positions as required.