[KainArkanos]

For some reason, either I have absolute bad luck with Beyerdynamic or their headphones are just completely incompatible with my setup. I run a JDS Labs OL DAC and a Massdrop O2 Headphone Amp, and only with Beyerdynamic headphones, specifically both DT990 Pros and DT 770 Pros, neither can handle bass whatsoever. It's not even the usual hair problem as I have check relentlessly for hairs and there is none. They always rattle and pop during bass no matter what. The only way to avoid it is having the volume so low you can barely hear anything.

Keep in mind that I'm not heavily invested into the idea of audiophile, I'm a gamer and well versed in computers first and foremost who also enjoys good audio, both when gaming and listening to music so I may not have realized a special nuance of these certain headphones.

 

[castleofargh]

a very likely possibility is that you're overdriving the O2. use the low gain setting! you can also lower the digital volume on your computer so the DAC sends a lower voltage, and compensate by increasing the volume on the O2.

 

[PurpleAngel]

For some reason, either I have absolute bad luck with Beyerdynamic or their headphones are just completely incompatible with my setup. I run a JDS Labs OL DAC and a Massdrop O2 Headphone Amp, and only with Beyerdynamic headphones, specifically both DT990 Pros and DT 770 Pros, neither can handle bass whatsoever. It's not even the usual hair problem as I have check relentlessly for hairs and there is none. They always rattle and pop during bass no matter what. The only way to avoid it is having the volume so low you can barely hear anything.
Keep in mind that I'm not heavily invested into the idea of audiophile, I'm a gamer and well versed in computers first and foremost who also enjoys good audio, both when gaming and listening to music so I may not have realized a special nuance of these certain headphones.

Do you have access to a receiver, if so, try plugging the headphones into it, see if you still have the same issue.
Disconnect the ODAC/O2 from the computer, plug the headphones directly into the PC's on-board audio (headphone jack), see if you still get the same issue.
If you still get the same rattle and pop, it just might be both headphones are defective (best guess).

 

[KainArkanos]

Probably both faulty. I tried them before out of the onboard sound and also through my old Soundblaster Z and same issues.