Monoprice Monolith M300 review

You get what you pay for with these cheap planar magnetic in-ear headphones

TODO alt text

Our Verdict

The Monoprice Monolith M300 are a wonderful sounding pair of in-ear headphones that come with too many compromises. From its heavy, unwieldy cable to its extreme discomfort, the Monolith M300 just aren’t worth the tradeoffs for great sound.


  • Balanced and detailed sound
  • Spacious soundstage
  • No amp needed to sound great


  • Extremely uncomfortable
  • Ear hooks break easily
  • Unwieldy cable

Most headphones on the market today use “dynamic drivers,” which is a driver technology where a copper wire, called a voice coil, is wrapped around a cone-shaped diaphragm. When electricity is sent through the wire, the diaphragm moves because of the electromagnetic field and creates sound. 

Over the last several years, another type of headphone driver has made its way into the mainstream: Planar Magnetic. These drivers work by sandwiching a very thin diaphragm with voice coils embedded in them between two magnets. Some advantages of this technology include lower distortion, tighter bass response and faster response. However, the trade offs are weight and being trickier to damp. 

With this in mind, it’s quite an achievement that companies like Monoprice are creating affordable planar magnetic headphones and have even miniaturized the technology to fit into an in-ear headphone: the Monoprice Monolith M300. 

After spending over a week with these headphones, we were blown away by their sound but, ultimately, can’t recommend them because of the many compromises Monoprice needed to make to get great-sounding headphones into this form factor at $150 (about £110, AU$193). 


If the design of the Monoprice Monolith M300 looks familiar, that’s because they’re a clone of the Audeze iSine series of planar magnetic headphones. The driver housings and earclips have been replicated by Monoprice this time around, however, we hope Monoprice invests in its own design for future iterations of the M300. 

With that aside, the design of the Monoprice Monolith M300 is a bit of a mixed bag. While the driver housings feel sturdy, the included ear hooks are plain awful. They’re uncomfortable, putting a lot of pressure on the back of our ears, and broke after just three installations and removals. 

Thankfully there’s also an included set of silicone “wings” that help the headphones stay seated in your ears – though they don’t do much to help the discomfort over long listening sessions. 

This discomfort stems from the fact that the nozzles are quite large in diameter. Combined with the fact that the headphones and included cable are extremely heavy for an in-ear and comfort and fit will be a challenge for many. 

Speaking of the cable, Monoprice decided to include a thick and heavy cable that we suspect came from one of its full-sized over-ear headphones – a decision we just can't understand unless it's a cost-cutting strategy from Monoprice. 

The Monolith M300 are open-back design, which means sound gets in and out of the headphone. You won’t want to be using these headphones at the library. However, the open-back design also helps with sound quality, which we’ll go over now.


Planar magnetic headphones are known for their excellent sound quality and the Monoprice Monolith M300 deliver: Tonal balance is near neutral with a slightly forward presentation and bass is a highlight, as it digs deep and offers good impact. Mids sound natural and aren’t muddied up by either the highs or lows. 

In terms of specific genres, vocal music sounds excellent with the Monolith M300. Highs are well represented and borders on being bright. This means music sounds exciting and detailed, but never sibilant. 

Soundstage is quite wide, especially for an in-ear headphone thanks to the open-back design. Imaging is also good, with good stereo separation and the ability to place different instruments around you. 

Overall we quite liked the aural presentation of the M300, however, those who want a slightly warmer presentation and more impact will have to look elsewhere.


In terms of sound quality, the Monoprice Monolith M300 punches way above its price range. These headphones sound wonderfully balanced with tight bass, sparkling highs, and a spacious soundstage. 

However, everything else about using the Monolith M300 was frustrating. 

We found the headphones extremely uncomfortable for long listening sessions and the included plastic ear hooks broke nearly immediately. The included cable is unnecessarily thick and heavy, making comfort even worse as it pulls down on the earphones. Even the included case was frustrating to use as you have to jam the headphones in, causing the sides of the case to balloon. 

For the money, it’s hard to knock the Monolith M300 too much as you get a lot of sound quality for the money. However, you’ll have to deal with poor fit, discomfort, and other quirks in order to really enjoy these headphones. 

Our advice? Save up $50 and get the just-announced Audeze iSine LX instead.