Would you mind explaining what this mod does as it pertains to the 700s? For the 800s it's supposed to tame the 6KHZ spike but I find pairing the 700's to tubes takes care of any treble spikes. I'm also using a warm DAC (Mimby) so it definitely helps any issues of sibilance.
I've seriously thought about upgrading to the 800's but I love that these cans are smaller, more comfortable (imo), and aren't overly fatiguing; fun but still preserves a good amount of detail. It also is better for my wallet because knowing the HD800's, I'd be buying lots of Jazz music on HDTracks in 24/192 and spending $40 an album. Modern music just isn't really well suited to the 800's from what I've read because mastering has taken a backseat to just loudness wars and so there really isn't much detail to extract in the first place.
Although I did enjoy the HD700 stock I found its treble to be a bit too thin for my liking. After installing the mod everything just fell in place for me. Overall sound is a notch thicker to my ears and I like it a lot.
If you haven't done so already you can read more about the mod here:
https://www.google.no/amp/s/everyda...ix-your-treble-woes-with-this-simple-mod/amp/