Been lurking on this thread for years, purchasing a HD598 based on MLE's impressions. Paired with the Mixamp, they've been awesome for the 6 years I've used them.
With the PS5 coming out and the uncertainty around the USB capabilities, I thought I'd replace the 598 with the PC38x, I wanted less hassle and wires with the in-built mic, and perhaps the Dualsense would more easily drive them considering they have a lower impedence, 28 vs the 598's 50 ohms.
However, upon using the 38x I'm not particularly keen on them. Personally, I find them really uncomfortable. Despite the fact that my head is kinda small, the PC38x are really tight, and I mean too snug to be comfortable for even short gaming sessions for me. My ears just barely fit in the pads, which is a strange sensation being used to the bigger roomier pads of the 598 for so long.
In terms of comparing the competitiveness, I had assumed, based on various reviews, the PC38x would have the advantage.
But testing repeatedly on MW2019 both in private match with bots and in regular public matches, I was better able to discern audio cues with the HD598. But the 38x was very close (and do bear in mind that I am very familiar with the sound signature of the 598s in MW).
Curiously, with the mixamp on the same volume, the 598s were louder than the 38x. Considering their respective impedance measurements, this was not what I expected. It could just be the emphasis of certain tones, but to me the 598s were louder in every respect, leading me to believe they were easier to drive than the 38x.
All in all the PC38x are great, but severely let down by its comfort. Despite its convenience over the 598, the latter is infinitely more comfortable.