2 Way Audio mixer 3.5mm Un-powered mixer, 2 to 1 Stereo aux 3.5mm line levels control Box mini passive mixer X21

I'm using this device to drive one set of powered speakers from two stereo line level sources: my computer audio output, and a Chromecast Audio device. I did not get the buzzing that apparently shows up in some applications, so I did not have to follow the instructions for getting rid of the possible buzz. Six+ months in, there is no evident damage to either audio source. It is super convenient to be able to use the speakers for two purposes simultaneously. As other reviewers have noted, there is some coupling between the two volume knobs (e.g. if you max one of them out you will silence the other) but practically speaking I have no trouble getting the volume and the relative volume that I want. While listening to Chromecast Audio, I can hear the computer's audio output too, clearly and as loud as I want to set it to.

I attached 2 headphone line's and I have to run the volume way up on the keyboard and PC to getjust enough volume in my headphone's to hear the music. Yes, I hear both but the "volume control" on the unit is worthless. Have to look into something amplified. This did not work regardless of the settings.

I used it originally to introduce a Bluetooth adapter to my speakers while keeping my Chromecast connected to the speakers as well. I did have a buzz with the ground noise isolator connected but when I removed it, the buzz went away.Now I use it to connect both of my computers and Chromecast to the same speaker system. No hum, buzz or static sound.

I needed a solution for mixing (2) PC audio outs into one signal that I could connect my headphones to. I decided to give this device a try despite some bad reviews.It turns out that this device works really well, has a nice metal case, inputs are metal and feel solid and the plastic volume knobs feel robust. There's no line noise, it does indeed mix the channels as advertised and it supports stereo for all inputs/outputs (I did not test reversing the path as the docs say is possible). One thing you need to keep in mind is that all channels need to already be amplified- if you choose an unamplified source the volume will be very low. On Windows 11, I had to choose my "Speaker out" option to get an amplified out from the Display port audio.The only issue is that, once the channels are mixed, only "Level 1" volume knob works and it reduces both inputs together. You can't use both knobs to reduce each input independently. This isn't a major issue for me, but seems like a miss on their part. I also had a stereo cable and a stereo adapter that came through in only one channel for some reason. I did find 2 cables that worked perfectly, so those other cables may have been faulty.Bottom line is that this device is great for my problem where a proper mixer could cost hundreds of dollars, but would be complete overkill. This device, being passive, doesn't introduce any audio buzz or sound quality reduction so going high end for solving such a simple problem is a waste of money.

This thing passively sums two audio sources together and has an attenuator knob for each source. There is of course no gain, the knobs simply attenuate the volume. Summing two audio sources together passively, you're going to lose volume, and this thing lost me a lot of volume. My headphone amp has more than too much gain, and with my signal hitting this mixer first, I just barely don't have enough. Removing the second source gives you some gain back, but what's the point of that? For what this thing is it works fine, you should expect some volume loss summing two sources passively.My issue is that there are four random DIP switches in-between the two knobs. Not documented in the packaging, not even pictured anywhere on any product page, and I have no clue what they do. Above all four it says "1k" and below them it says "4k7". I suppose that's probably referring to different resistors? Flipping the first switch upwards seems to increase the volume, flipping the last one seems to as well, the middle two I have no clue. Doesn't look like it's "1 left 1 right 2 left 2 right" so I've got no clue lol.

Great construction, well built, and worked. connected Audio output of Carpuride Apple play unit ( Also bought on Amazon W103 Pro) to one input, and output of i phone through a Dragonfly cobalt DAC from an i phone 15 to the other , to the Aux in on a 2015 Honda Oddness. Also ran the output through a line filter also purchased through Amazon. Now I can combine signals from Both inputs, adjust Volume levels, and hear Lossless music from i phone, and directions at the same time from car play, avoiding the Loss in Music you get from, Wireless, and gain the HI Res, lossless you get from an external DAC. Can' take picture with Phone in Wireless charger also bought on Amazon, hooked to DAC, Also bought on Amazon, as I am taking pictures with phone

Its pretty straight forward, easy to set up, and flip the switches for a higher volume; however its just quiet even with knobs and all settings maxed out.. and after weeks of use, its begun to get more quiet gradually. It works for great if you don't mind quiet audio.

This worked perfectly for me connecting the audio output of two laptops into a single pair of powered speakers.The key here is “powered”. This mixer has no internal amplifier, so it will obviously add a bit of loss to the signal (although nothing perceptible to the ear). Your results with unpowered headphones will likely not be as good.Also, one reviewer stated that the volume knobs didn’t work independently, that is not true. Each knob correctly controls the volume of its input channel.