I know many of you don’t believe that cable swapping is worth it for sound quality unless switching to balanced. Considering that HD6XX is a rebranding of 650 and costs 200$ less, the cable would be an obvious compromise. So I ordered the HD650’s official replacement cable. I was not going to expect any massive changes to sound, but was still curious to try out. I tested with FiiO K5 Pro and 320kbs mp3 files (not a high end setup, but certainly not bad).

The 650’s cable determinates to 6.5mm jack instead of 6XX’s 3.5mm without the adapter. I don’t know if using the adapter could affect the quality of signal.

As for the sound difference between 6XX and 650 cables: As expected, the difference was not dramatic, but noticeable by trained ears. The bass response sounded tighter and punchier with 650 cable. This made music in general sound slightly cleaner and more dynamic.

But realistically, the cable switch is not at all necessary with 6XX. But if you want a tigher bass to improve clarity, the 650 cable could give you just a tiny improvement.