I have a few scanners feeding online feeds such as LiveATC.net. Some of these allow no way to listen directly to the scanner in my shack without listening to the feed online. To solve this, I bought a Behringer MicroMix MX400 mixer. It has 4 inputs and one output. With audio splitters on the scanners, it was an inexpensive way to allow me to easily listen directly to the scanner audio without disconnecting the online feeds.