Purchased a pair of OG velour pads because I wanted the mounting rings and, to my surprise, they don't sound horrible on the HE6SE v1.
First things first, these things are cock-stiff when you first get them. This combined with the thunder thigh clamp of the V1's headband and I got a headache after like 30 minutes. So I took them off and started making my way around compressing down the foam with my fingers to break it in. It actually worked! A lot softer now.
Some impressions vs stock pads:
They're definitely way brighter than stock pads, and not for the treble faint of heart. Fortunately though, the rise in treble is focused more towards upper treble, so the nasty 4k peak doesn't get boosted. All the while filling in 2k to 3k. Nice.
Not so nice is that they start to roll off 50hz and down, but they sorta make up for it by boosting midbass, which gives it some extra tactility and adds some needed warmth. This tactility also carries on from the bass onto the rest of the spectrum? With these pads things like guitar plucks come through with more weight than they do with stock pads. This is something I miss dearly form the old HE line, and these pads bring some of it back.
This is running them off a Jot 2. The results were a warm/bright headphone.
I then tried them with an Emotiva A-100, which is warmer/fuller sounding than the Jot 2. It brought down a lot of the added brightness form the pads and gave the bass even more thump. Everything I said about tactility got turned up a notch or two, and it got waaay easier to listen to without all the harshness.
The end result is reminiscent of an HE-500. Which is nice considering the HE-500 is probably my favorite headphone. No, it still won't have the note weight and sheer grunt of the old models, but this is the closest I've gotten to it thus far.
Tl:dr, HE6SE + velour + warm amp = copium HE-500?