I found this whilst looking for other components. Might be of some use to the DJ’s here with analogue mixers – other than the one with IR position sensor they all appear to be the old skool type, where the wiper of the fader is connected to signal earth, and the signal from the opposite side deck to where the fader is going is connected to the track in that position. (This makes sense if you think about how the crossfader works, as what it is doing is sending the signal from the opposite deck to earth rather than into the program audio bus, whilst the deck you want to hear is getting all its audio sent to the mixer).

Sound & Lighting – Spares for Sound and Lighting Equipment