You can get a similar effect, but in a different manner, with attempting to plug a CD or MP3 player into certain mixing desks. The obvious approach, when you ha

You can get a similar effect, but in a different manner, with attempting to plug a CD or MP3 player into certain mixing desks. The obvious approach, when you have a 3.5mm (1/8") stereo jack from the device, to attach it into one of the 1/4" line input sockets with a suitable stereo adaptor. In most cases with older desks, this will be fine (you'll only get the left channel from the source). Some newer/smaller desks have a balanced jack input instead or as well as a balanced XLR, and plugging in an audio source will get exactly the same effect as described in the thread, since the left and right channels will be treated as a balanced pair and subtracted. Cheapest approach to connect such a device to a mixer is a 3.5mm to 2x phono plugs and a pair of phono to 1/4" jack adaptors, connect to two channels on the mixer, and fully pan left and right. (Never really thought about it before, but here in the UK it seems perfectly normal to refer to 1/4" and 3.5mm plugs at the same time)