I tried mine only on E10K and K3. Do they "scale" with better gear in your opinion?

Because they are. They go completely over the ear and are very comfortable. Big improvement in that regard.

They do for sure affect sound, but not by much. The sound appears more open and spacious, it gives the illusion of improved soundstage. And about sound signature - I used lately a mild EQ to further flatten the sound, and with the the new pads i preffer it without EQ. So I guess it works for me, but that's rather subjective.

I found the ZMF cowhides not worth the price and shipping, Brainwavz offered localy only "vegan" products, so I ended up ordering from China and I'm pleased with the decision. The second "upgrade" should be a cable (cmon, 3 meters for desktop is way too much), and with the little adapter I am not limited to brand specific.

It will work, but will sound like sh!t. If you are looking for a practice amp, I'd suggest digital amps (if it's not too late). Used Blackstars ID series, Boss Katana, Yamaha THR etc. They don't sound amazing, but still fine for what they are (talking purely about headphones out).

Used to listen to music approximately 5 hours per day. Family and professional life catched up and now I feel kinda depressed. I need music to recalibrate myself. Good weed while listening wouldn't harm either.

No wonder we appreciate good sound that much. It's such an important part of my life and good gear makes the experience even better. It isnt't expensive either, because of how long it can last.