LINE5 Multi-channel Headphone Audio Signal Switcher Stereo Headphone Amplifier Black

Perfect, once I employed this solution to hum.Solid little unit, looks good, and comes with ample color coded 3.5mm cables. Works well (as others have noted, it is used to select 1 of 4 inputs, and sends that identicall to up to 4 outputs. Not used as a mixer in the standard configuration.But what about the hum? What good is a nice looking, solid unit where a hum is present in the output? Punch line: TWO ground loop isolators in series completely eliminated hum; one did nothing. I am pretty electronics-savvy, but find this puzzling--My setup: I have powered desktop speakers. I wanted them to either be driven by my iPhone headphone output, or by the computer speaker output. Both these inputs were therefore plugged inot the back of the unit, and the one output to the speakers came out the front.The problem: serious hum. I had been warned that there might be hum, so I had ordered the mpow ground loop isolators that came as the "people who bought this also bought...." recommendation. On a lark I bought two.When I noted the hum, I put one isolator on the output (between the output of the LINE5 and the input of the speakers. No change in hum. Hm. Tried the other one. No change. Hm. Put one on each input. (I think--can't fully remember the configurations). No change. What a bust!In desperation: put both in series on the output. In other words, from the LINE5 output: a 6" extender that came with the mpow isolator; the mpow isolator; a headphone cable to reach the speakers; the second mpow; then the last 6" adapter. Note that the mpows were oriented in the same direction (not that polarity should matter for a 1:1 isolating transoformt). No hum. At all. Success! I am listening to it now. **NOTE: When writing this review, I tried again to reproduce, and this time one isolator on the LINE5 output was sufficient. I am not sure why (maybe there were polarity issues, or one of the ground loop isolators was defective--though I had tested for that).Bottom line; when you buy this, add one (or two) isolators. Adds to cost, but you will then get what you intended.

This is a very simple device and should work perfectly fine. The one I received was not well-made. All 4 audio channels bled into one another to some degree. So if you plugged 4 audio channels into the 4 Ins, you would hear the primary channel you're set to, then a faint version of the other 3. No shielding at all. Based on other reviews, I think some versions of this product work exactly as expected. Mine did not.

Purchased with the intent of using it as a headphone switch for a single source. Works well for that purpose as there appears to be no added noise. My set up is a SMSL M3 dac/amp plugged into the front of this device with my headphones plugged into the back.How does it work? The four front 3.5 mm jacks all work simultaneously and the switching occurs with the four 3.5 mm jacks in the rear. So if you wanted to switch between multiple sources so that multiple outputs work at the same time on the selected source, you would plug your source in the rear and your outputs to the front. If you wanted one source and to switch between multiple outputs, you would plug your source to the front and your plug your outputs in the rear. Plugging multiple simultaneous running sources at the same time does affect sound quality though.I do have issues with the build of the product. The major issue being the spacing/size of the product. The spacing of the 3.5 mm jacks is too close, especially in the front. Depending on the size of your plugs, you might not be able to utilize all of the jacks available. Minor issues I can live with are how rough the edges of the metal feel and how the indicator line on the selection wheel don't line up with numbers printed.The device also comes with four, 3-meter male-to-male 3.5 mm cables that feel pretty cheap; but they are least functional.

Giving it 3 stars because I don't know if the issues is correctable or not.I am a ham radio operator, and I have an HF radio and a VHV/UHV radio as well as my PC.I have all 3 coming in the back of this thing and one output, my headset on the front. It DOES work, but I get a 60 hz hum. If I am actually listening to something it is not really noticeable. And I have noted on my PC (iMac) that if I wait a few seconds the hum goes away but as soon as I do something, like send a text and it "swishes", the hum is back until it "times out" again. Not sure what happening here.I do this so I can listen to my "stuff" without bothering my wife. Radio, talk or CW, for the uninitiated, can be, I am told, quite annoying. Go figure.I am going to try some toroids filters and see if they help at all.Update: 01/15/2017I have two (2) ferrite chokes on the power cord now. No change. I still get my hum. Annoying but not drastically so.What is a real problem, is that I use this to have my headphones connected to the front and my iMac and Yaesu 450D connected on the back side. I "can" switch between the two and hear different audio. The problem comes in when I am doing Morse code on the 450D the imac's audio sometimes disregards that I am connected to the headphone jack and plays through the speaker. AND/OR it will start Siri (who gets totally confused and says "I don't understand what you just said" and it also starts iTunes player. I don't pretend to understand, I just report what I have observed.There may be other/different versions/devices that can provide this functionality. I would suggest forgoing this device for one of them. I will, sadly, be attempting to return my device.