Whirlwind IMP Line Level Combiner

The IMP Line Level Combiner is what you use when a stereo source has to arrive as one mono line and the two original signals must stay isolated from each other. It is the right box for feeding a player into a mono system or a single console channel.

It does more than tie the two together: it also compensates for the 6 dB of gain that appears when two in-phase signals are summed, so the level lands where you expect. Isolation between inputs is better than 42 dB, and a ground lift switch breaks the shield connection between them. Connections are two female XLRs in, one male XLR out.