Thought I would give those pads a whirl, too. They arrived today and I did some listening and measurements to see how they stack up against the dozens of other pads I've tried on my HE6se V2. Some select comparisons are below.
They are quite similar to Hifiman's own FocusPad, although they are slightly thicker (full dimensions below). Velour on the part touching the head, pleather around the outside, and perforated pleather on the inside walls of the ear hole. Pretty comfortable overall. Foam is slightly softer, but also less dense compared to the genuine FocusPad. I would expect it to wear out faster but, you can buy 3 pair for the same price as genuine ones, so I guess that's not really an issue.
Ali FocusPad Dimensions:
Outer diameter: 104.5 mm
Ear hole diameter: 62 mm
Thin thickness: 20 mm
Thick thickness: 29 mm
And now the real one for comparison's sake. Biggest difference is that it's thinner.
Genuine Hifiman FocusPad:
Outer diameter: 104.8 mm
Ear hole diameter: 60 mm
Thin thickness: 15 mm
Thick thickness: 23 mm
I started off the test by swapping them with the round velours that I was using and see what I noticed. Everything seemed "softer" and I found myself turning up my amp more. Bass seemed more less the same, maybe slightly less tight. Quantity seemed about the same before I turned it up. I noticed on a couple of songs that some lower treble was jumping out at me more (and making me turn down the volume back down). Imaging is good, typical for angled pads. Everything sounded pretty good and comparable to what I'm used to, but less focused, for lack of a better term.
I took some measurements on my homemade rig after I was done listening. Obviously, this isn't comparable to any other rig's measurements since it's a flat plate, etc., etc.
Stock PeliPad (red) vs. Ali FocusPad (green)
Similar, but improves the 1-3khz dip slightly and has a lot less energy at 4-5khz and 8-9khz.
Genuine HFM FocusPad (blue) vs Ali FocusPad (green)
This one is closer than the PeliPad, but still show less energy at 3-5khz. Pretty much the only major difference.
Genuine HFM FocusPad-A (pink) vs Ali FocusPad (green)
The FocusPad-A (the one with mesh/knit instead of perforated pleather in the earhole) is closer to the Ali knock off but still has a little more zing at 3-5khz.
HFM Round Velour (orange) vs Ali FocusPad (green)
This is my fave pad on the HE6se V2. To my ears it has a little more bass thanks to the slight recess at 300-800hz (I normalized it here to show what my ear hears, roughly), less of a dip at 1-2.5khz, and a little extra energy at 4-6khz. I'm guessing this is what the "softer" sound that I was hearing since that 4-6khz is in the ear gain region and it would take a step back. The larger dip on the Ali pad at 2khz might also contributed.
Generic non-angled sheepskin leather pad (red) vs Ali FocusPad (green)
For good measure, I compared it to a solid leather pad since a good number of people here have leather pads. This isn't representative of other pads in detail, obviously, but most solid leather pads I've tried have similar aspects to varying degrees of severity. The genuine leather pads almost always have a bump at 800-1.25khz, which to my ear means there is less bass (if you EQ up the bass anyway, this wouldn't matter though), does a good job raising the dip at 1-3khz though. And for some reason, most leather pads show a dip at 7khz specifically which takes some of the bite out of the treble compared to non-leather pads.
The knockoff FocusPad from Ali express is a decent pad, especially if are looking for something similar to stock but you find the 3-5khz region problematic with the stock PeliPad. Additionally, If you adjust your volume relative to this region you might also turn it up more which would increase the perceived bass thanks to the loudness curve. For me, it's not going to take my velour's spot as my go to pad for the HE6se V2 at least, but I have plenty of other Hifiman headphones to try it with. Maybe the HE-500 would be good since I really like the FocusPad-A on that one.