I have a Crack with Speedball and here's my observations.
While not exactly the same, I have two pairs of the DT770 Pro 250 ohm models and I replaced the drivers of one of them with the 600 ohm drivers (
https://www.markertek.com/product/byd-935037/beyerdynamic-935037-600-ohm-headphone-driver). Since you can't buy the DT770 Premium 600ohm model anymore, and trying to find a pair is next to impossible, I just did "headphone surgery" and created my own version.
Overall I thought it was a worthwhile upgrade. I've read that the DT770 Premium 600 Ohms were bass light, but not in this case, it's all there just like with the 250's and it almost seems like there is a little more bass, but it is more tight and well controlled. It was subtle, but noticeable.
The only thing I don't like is that they turned into treble cannons in the process, but I ordered Schiit Loki (equalizer) to hopefully help tone that down. Even though they are treble cannons, the treble is so much more detailed than it was before, it seems like I can hear more separation between instruments and vocals.
It has to do with damping factor, here's a good article on it:
https://www.innerfidelity.com/content/comparison-beyerdynamic-dt-880-32-ohm-dt-880-250-ohm-and-dt-880-600-ohm-headphonesOverall the difference was noticeable with the increased level of detail and the tighter bass, but an EQ is needed to tone down the brightness.
Hope that helps.
