I've been doing home project studio recording for over 20 years and it is rare that I am impressed by a budget item which sells for far less than most of the prosumer / pro-audio equipment with equivalent functionality does. Usually the lower price is achieved by cutting corners, understandably so, but the solid build quality of this unit is well above the standard for a headphone amplifier; A popular company makes a similar 4-channel headphone amp with no frills, just 4 headphone outputs, each with their own volume knob (potentiometer). Sells for a similar price. This product gives you both the 1/4" TRS full-size "phone" connector jack AND a 1/8" (3.5mm) minijack phone connector on the input and on every output - I have never seen that in the pro audio world. Pro monitors will often have all 3 types of input connectors (XLR, RCA, TRS) for so its usable with any type but those are wired in paralell for simplicity and cost reasons - not on this product! Paralell wiring would've been acceptable but its inferior because plugging different types of headphones into both jacks simultaneously will produce different volumes for the headsets, nixing the benefit of this product which is the individualized volume control knob. On this product, using active electronics, both size jacks may be used simultaneously, with no impact on the other, and this is true for the input too! That means if you plug an audio source into both the 1/4" and 1/8" input simultaneously it doesn't "half" the volume of each - they're both heard at full volume which doesn't change if you remove the plug from the other. Typically small, basic headphone amps of this size/price never have a 2nd (auxiliary) input and this does (they don't even mention this in the pretty good manual, I expect because its provided as a convenience facility and there's not a knob to control the two inputs' gain independently) - but this is a lovely bonus capability.The volume control is great, you get a linear curve and I don't hear any noises when moving the potentiometer! Even prosumer mixers less than $100 typically have that problem. The mute button is a nice touch - so that you can temporarily mute and then when un-muting the volume is still exactly as set. I also love the mono feature because these days not enough recording engineers check that the mix will sound OK in mono (not have phasing issues) which is important for live audio etc.I also appreciate that it uses USB for the power input - lovely to get more pro audio gear onto this standard rather than searching for proprietary DC adapters for each device. I will have to look up this brand to see if they make any other good products - in this category there's a recent flood of low-cost, no-name-brand cheap units which usually will perform acceptably, if only OK and not well, usually also the construction feels shoddy, lightweight plastic is used and the knobs are wobbly from day 1 - this, on the other hand, is like the high-end audio gear with the nice heavy metal case, knobs don't wobble, this company even offers an 18 month warranty! May not seem like much, but at this price it's an excellent value.

That every port offers both 5 and 3 mm jacks saves a lot of hassle.The knobs feel fine, but I'm disappointed in their labeling. Foremost, they are labeled as both "volume" and "gain" running from 0 to 12 with a labeled 6 and pips every (I presume) 2. Were that "gain" label valid it would suggest that at 0, the output should be what I'd hear if I plugged the headphones directly into the source. This is not the case. "0" is no output, and I estimate that the "4" pip is about neutral to the input level. "Volume" is the label describing the knobs' function. This is not a surprise, but if "gain" is going to be labeled, I would like for the gauge to actually reflect dB difference both up and down.The knobs are color coded, and except for the cyan of Out 2, the colors are dark enough that it is difficult to read the knobs in low light conditions. I'll probably touch some white paint on the knobs and scales for my own convenience.Testing on a small MP3 player, with its volume maxed my 62 ohm impedance headphones are loud enough for listening but isn't going to jam. This amplifier is enough to bring it to loud but not unpleasantly so. Another set of headphones at 32 ohms impedance did get loud enough that I wouldn't leave them on my ears.

This 4 way headphone amplifier or headphone splitter is awesome and perfect. High quality design and materials. Made from a quality steel material. Strong and perfect. This device is amazingly helpful for many devices. It is compatible with laptops, PCs, guitars, keyboards, sound mixers, and amplifiers. Perfect. Super happy. Awesome and vibrant sound. Amazing. Crisp and clear. Low noise only occasionally, however no sound distortion. High fidelity. Professional or amateurs like us. Two things to note with this device. It has an input for a dynamic microphone (mic not included), does not support a USB connected microphone. Another helpful tip that we are learning for the first time that others may already know, the gain knobs actually control the volume, not a separate volume knob. Super fast and easy to setup. Plug and play. Corded electric. Adjustable. Stereo or mono. All inputs or ports are clearly labeled on the device. Super helpful. Super fun to play around with musical instruments. Perfect for many occasions. Versatile. 4 channel sound mixing, which we are currently learning how to use. Small and compact for easy portability. Truly enjoying all the different and fun features. Would make a fabulous gift. Would definitely highly recommend this awesomely sounding and crisply clear audio enhancing device. Overall, we are giving it’s quality, strength, durability, usefulness, ease of use and learning, fun, more active gameplay and musical experiences, plug and play, high quality audio, low noise and distortion, value, usefulness, versatility, perfect for many occasions, helpfulness, functionality, and awesomeness ⭐️⭐️⭐️⭐️⭐️.