This is a review and detailed measurements of the Nobsound MC-103 Pro 3-IN-1-OUT XLR Audio Switcher. The unit I have came with the brand Douk on it so that is what I used in my notations below. I suspect multiple companies put their name on it. I purchased it a few days ago from Amazon. The MC-103 Pro costs US $59 from Amazon including Prime shipping.This is a sturdy but small box with a large input selector on it:The selector has a scratchy feel to it but does the job. The box is too shallow to be able to control the heavy XLR cables I was using with it so had a tendency to tilt back.The back has just the connectors you would expect:This is a passive selector/switch so there is no need for power. As such, it should be bi-directional although I just used it as three inputs and one out.As usual we start with our dashboard with 4 volts in, and 4 volts out (for XLR/balanced connections):What you are seeing is the performance of my Audio Precision APx555. Indeed, I selected internal loopback in the analyzer and got the same results. This is how it should be but it is a relief seeing it in numbers.Next I checked crosstalk, again with the MC103 Pro and with internal loopback on the analyzer:Marvelous!Note that which input you use doesn't matter either.Signal to noise ratio was just a hair worse than internal loopback:For last test, I feed one input (not selected) white noise and tested what happened when I turned that on and off:So there is 10 dB of bleed from one input to another. The still gives us signal to noise ratio of 124 dB which is well beyond any dynamic range we would require. If you don't want to see such a degradation, just don't activate the other inputs at full amplitude.The Douk/Nobsound MC-103 Pro does what you expect it to do: switch between three balanced inputs with essentially no degradation even when held up to the high standard of my audio analyzer. If you don't need gain/volume control or remote control, it would make a nice "pre-amp" replacement.Needless to say, I recommend the MC-103 Pro. I plan to use it to select between active speakers for listening tests.------------As always, questions, comments, recommendations, etc. are welcome.Went to see a movie with my wife (last Star Wars). It must have been one or two years since the last time we went to a theater. Enjoyed it good and lamented that I am too poor to go movies more often . So would you pleasesome money so I get more of a break from you all using