Don't underestimate this.
I didn't actually plan on buying anything like this at first and I think that is why their aren't any other reviews at the time of writing this. My setup includes a DJ controller which can only primarily be used with its own built in audio interface. I have another audio interface which I use to do most of my production work as it has built in metering and has better latency as it is a firewire interface. Yet I only have one pair of active studio monitors. This created a problem. Therefore, in order to switch between using these two audio interfaces, I had to unplug and replug cables to my studio monitors a lot depending on which interface I needed to use. Then I thought wouldn't it be great to have some sort of way to switch without having to resort to doing this. I just plugged in the output of the two different audio interfaces into the inputs on the Hosa SLW-333 and then connected the outputs to my pair of studio monitors. Problem solved! All I have to do now is use the big knob to switch between hearing the two different audio signals. This is how I use it, but I can see how this might have other useful applications. This device doesn't require power and doesn't introduce noise which is a plus. It just helps control where your audio signal is going with a very simple interface. The strange thing is I haven't seen anything like this from any other audio manufacturer. The only thing that came close to this on this website was the SplitMix4 from ART(Audio Research Technologies), but that had gain knobs on it which would have only complicated my problem. I'm not sure why others aren't making stuff like this, but this is definitely an awesome yet overlooked device. Thanks Hosa!