A rare opportunity has come up to compare to units of the Audio Technica M-50 headphone, both in stock condition. One headphone has clocked hundreds of ours of, while the other is brand new from the box. For this test, both headphones are plugged in at the same time to both headphone outputs of the Grace m902 DAC/Amp.
Are the two any different? Is the difference significant enough?
Here is what I found:
- The new unit significantly has a more closed and narrower soundstage.
- The new unit presents more prominent treble.
- The new unit presents a more forward vocal. I actually like this rendition better.
- The new unit’s frequency extension is less smooth on both ends.
- The new unit’s bass area is significantly less clear in texture.
- The new unit’s bass punch is stronger.
- Surprisingly, the new unit’s bass is not exactly more boomy than the old one.
- The new unit has an inferior instrument separation.
- Playing a test tone, the new unit is ~1dB louder than the old unit. (I used a 440Hz, 1kHz and a 4kHz continuous tone)
The difference is significant enough that I can tell immediately if I’m listening to the new unit or the old one, even without looking at the mark that I made in the cable to differentiate the two.
Now, the brand new M-50 was then put in for a several hundreds hour of burn in, and after a few weeks I went back and re-did the comparison.
This is what I found:
- There is an improvement due to the burn in, with the new unit now being smoother and less constricted, having a better instrument separation. If the new unit was inferior in instrument separation, now it pretty much equals the new one.
- However, the two headphones still sound slightly, yet noticeably different. The new unit has a more forward presentation. More forward mid and low treble, and punchier bass, where the old unit is noticeably more laid back. Playing some mild rock tunes, the new unit carries the energy of the music better, where the old unit sounded less focused and more laid back.
The difference is very interesting, and me and Hadi thinks that the different production batches account for more difference between the two headphones than the burn-in did. Although the burn-in makes the new headphone smoother and improves the technicalities slightly, the different production batch literally gives us two slightly different versions of the M-50 sound. I asked some other enthusiasts to listen to the two fully burned M-50s. Some people can notice the difference, and some other cannot. So clearly, we’re talking about very subtle things here. And yet the difference due to the burn-in is even more marginal than the production batch difference. Personally, it is very hard for me to note the difference, had I not have the second M-50 to compare with. I think this explains why a lot of people consider burn-in as more of a placebo effect. Yes there is a difference due to the burn in, but it’s very slight. And I do think that placebo plays a bigger role here than what actually happens physically with the drivers.
But of course the effect may be different from different headphone models. And since there is no way that I can do the same test on all the different headphones, anyone can still come up and claim that a 1,000 hours turns his headphone into a giant killer.