Big ear cups are a must! It’s nice that the HD series, and many other brands/models, have replaceable ear pads that are even more comfortable. The only issue with open-back headphones is there will be some sound leakage. My wife could hear whatever I was playing and thought I was ruining what hearing I had left. That’s why I bought the Meze. I also have the Sony WH1000XM4 headphones. They’re a little tighter around the ears but with careful positioning, reduced volume, and possibly reduced mids if you have EQ control, they sound nice and will also work (and give you a wired or wireless option).
I agree that a small headphone amp for your home or dongle dac/amp for your phone or tablet can make a big difference in the sound quality. The price/performance on these devices is pretty amazing these days, well, the price in the pre-tariff days anyway. I haven’t shopped lately but there are lots to choose from on Drop, Apos.Audio, and Amazon in the $50 range and up.