I'm using this cable.
https://www.amazon.com/NEW-NEOMUSICIA-Replacement-Compatible-Headphones/dp/B01LYS3MM8
I've actually been using this same brand and model of cable on an HD650 and a Q701 as well. It's a good cable, especially for the price. I'm not a believer in cables doing enough to bother spending $100 or more on a cable.
The Elear needs power, but not a ton of power. I feel that a headphone at this price point and this capability deserves a decent amp and a decent DAC, with that said, I don't believe that you need to spend a ton on either. I use a Topping NX4DSD for mine on low gain and never have to exceed the 12 o'clock position. I've had this amp/DAC for about a year and a half and it's always done me well.
The day I got them I listened to them first with my phone and a supposedly crappy Hidizs Sonata HDII USB-C dongle and only needed about 15 to 18 out of 30 to get them to be plenty loud. I have a Meizu Pro dongle coming that I plan to use with my Elear as well. 3x the power of the Hidizs, and it measures better in every way from what I've read, and it's just built better. I still plan to mainly use the NX4DSD plugged into my laptop, but there may be times I use these with my phone and the Meizu Pro dongle. I figured when I wanted to use a dongle the Elear deserved better than a $26 Hidizs Sonata HDII.