One problem I have with recommending headphones is that the definition of good and bad is so... subjective.
And recently someone asked, "Are there any tools out there to compare two headphones against each other?"
Yes there are, and Dr. Ir. Stéphane Pigeon has created one of the coolest sites that lets you do just that and more!
The Ultimate Headphone Test on AudioCheck.net is a one-stop resource for testing out your headphones at home.
In my opinion most of these tests are best done as a comparison. So, if you only have one pair of headphones, it may be hard to know the difference between "good" and"bad" quality because you'll have only one reference point. With that in mind, I put my daily driver, the Audio Technica R70x against my less frequently used M50x. Both are awesome headphones to pair with any ModMic to create the ultimate headset. My results are below.
Before you start, do NOT turn your headphones up to unsafe listening volumes for these tests. Some of the tests will play sounds outside the range of your hearing. No matter how loud you make your headphones you won't hear anything, but the sounds you can’t hear CAN damage your hearing!
R70x Frequency Response. Source: Inner Fidelity
To hear the lowest bass and highest treble you need two things: The ability to hear the sound and the ability for your headphones to reproduce them. While this won't tell you which is which, when comparing two headphones against each other this test can help inform what pair is best for you. This difference between hearing ability is part of the reason two people may have radically different ideas on what the best pair of headphones are.
To take this idea of hearing as a factor a step further, this test allows you to learn a bit about how where your current headphones may be falling short of your hearing. By turning the volume down pretty far (it may take several tries), you can hear where your particular headphones may fall out of your hearing range. By finding headphones that are louder in the ranges you have trouble hearing you may find the perfect pair!
Use this test to see how your headphones are holding up. Make sure to turn up you volume, but not to an unsafe level. I increased mine from 21 to 31 and that was plenty to hear a problem. The noise you'll hear will likely be a rattle or buzzing noise, almost similar to how a grounding problem sounds. The test may show signs of wear and tear on your headphones, or even a manufacturing defect. A fantastic test to do when you first get a new pair of cans!
I just love binaural audio tests, and even though I JUST clicked on the button I still thought someone was knocking on my door and almost took my headphones off to answer it! A great tool to test how your headphones handle directional audio in its most simple format.
Dynamic Range Example, Source: Unstopable Recording Machine
This test is more about how well you are isolated from outside noise than it is about anything about how your headphones reproduce sound. To get an accurate comparison you need to have two headphones playing back sound at the same level, which may require a noise meter to get perfect, but at the very least it will take swapping back and forth a bunch. Once you have it dialed in you can see which one allows you to hear "quiet" sounds the best, or to use the test name, to hear the dynamic range between its peak audio and its lowest audio.
There's several other cool tools and many other interesting tests to take on the AudioCheck site! For instance I learned that my (questionable) hearing couldn't distinguish between 8bit and 16bit audio tracks. Huge thanks to Dr. Pigeon on creating this awesome resource! Check out all the audio tests at https://www.audiocheck.net