Pyle 4-Channel Portable Stereo Headphone Amplifier - Mini Earphone Splitter Amp with 4 ¼” TRS Output Jacks - Independent Volume Controls - High-Quality Audio for Studio & Stage - PHA40

So far I have only tested with one of the line outs but I will be testing the other soon with additional headphones and cords. Quality is outstanding, I compared several headphones on output 1 and compared with a Polk Surround Bar, even modest over the ear headphones sound as good or even better then the 300$ Soundbar. I feel the quality of the amp is more then adequate as the audio sounded rich and clean to my ears. Obviously headphone quality varies dramatically and I tested with the Sony MDR ZX300 my old ISymphony Noise Cancelling and the Seinhesier HD 201. The change in headphones was very interesting to pick up the small differences in the similarly priced headphones. I thought the bass response on the Sonys was nice but I like headphones that fully enclose the ears to block out noise, amazingly scenes with thunder and base were very good, better then the subwoofer was producing. Surprisingly the Sonys were not bad for the price still I expected a little more based on the reviews I read. To get much better performance you need to likely spend at least 70$ and I would love to test the Sony 7506's at some point in the future.Back to the Amp, it serves its purpose well, volume only needs to be at 1/3 for the Sony headphones to be loud, plenty of power for all the Cans I tried. Looks nice and volume controls work well being on top. You will likely need 1/4 adapters as this unit takes full size plugs. Really no complaints for the price, I needed an amp to go from my Digital to analogue converter so I could get audio of my TV on headphones, this way the kids can sleep and I can use my new Plasma to watch some movies at night. For now I'm outputting from my Sony Bluray player which has a Coax digital out while I wait for my optical dual output adapter to arrive. Once that's in I will be able to have audio on the sound bar and headphones at the same time from all inputs to the TV. Figured it was better to go dual output then use a Toslink switch. Its surprising to me that some TV's now only have a single digital optical output.Anyways to sum up, for 17 bucks you get an amp that powers four sets of headphones from a single 1/4 stereo jack source, just make sure to buy some adapters and long cords or hook up your wireless headphones and you should be all set. I imagine this unit would also work well for labs and you could also further split with y adapters, I did this briefly so I could compare two headphones side by side, you will need to obviously crank the volume up though if your driving two sets of headphones from a single jack. I imagine ear buds would need very little juice to power, mine were all over and on the ear sets and had plenty of power from the amp.

I believe several of the negative reviews should be taken with a grain of salt. Likely some of the users are simply not connecting things properly (e.g. several comments about only the left channel working suggest plugs not fully inserted, likely the 3.5mm plug is not completely inserted into the 6.3mm adapter, as many of the adapters require significant force to make the correct connection). I do sympathize with users who have legitimate problems with non-functioning units, as the price is so low as to make shipping costs for repair or replacement hardly worth the bother. But then, we should be happy that the price is so low!This is a low-power unit, not intended for speakers, and not really great with low-impedance (e.g. 8-ohm) headphones. Even with 32-ohm and higher headphones, you will likely be disappointed if you want to really crank up the volume to eardrum-splitting levels, particularly with several headsets. The user guide states that the output impedance is 80 ohms, but in fact it's at least 470 ohms, because there is a 470 ohm resistor in line with each output connector (I made oscilloscope measurements, and opened the mixer to visually confirm the resistance) That will seriously limit the current to the headphones (but that's necessary, because the very tiny integrated circuits could otherwise overheat), and for inefficient headphones with very low impedance, will likely give somewhat muddy bass and noticeable distortion at even moderate sound levels.BUT - what do you think you are getting for less than 20 bucks? This is a very capable device, producing quality sound at moderate levels with appropriate headphones. Mine is well-constructed, no issues at all. I can barely detect a miniscule amount of noise when there is no input and the volume is cranked all the way up, and with 100 ohm headphones the volume level is very satisfactory and the sound is very clean. If I were an audio professional, I might look for something with better capabilities, but I would be paying a lot more for that, and I have no need for it. Five stars.

Just tried this headphone mixer last night with two headphones while recording.....It seems to work ok and easy to use.... But like most of these electronic devices, for some reason they don't connect as well when plugged in all the way, so be sure to plug your headphones in each jack about 3/4 in and leave some of the plug out...😁😁For the price, not a bad to deal!