Unpopular opinion- no one pair of headphones is the "be-all end-all" or headphones. Each pair works differently with each person, and you just have to try things out to see what works for you and your setup. Even the best most "flat" headphones aren't perfectly flat, otherwise all "flat" headphones would sound the exact same, and there would be no difference between different brands of these headphones.
I use a pair of CCA C10s with my AxeFx, and after a month or so of getting them to be comfortable in my ear and breaking in the speaker, I love them. Adding a correction curve in the global EQ (thanks autoEQ), and I get a great sound that I'm confident in, and I love the tones I can get because of it. Similarly, I use Audio-Technica ATH M-20x's for my desktop rig, and get great results from them too. I also use a correction curve (autoEQ and Equalizer APO), and love the way it sounds and feels. Both of these headphones are inexpensive, but I like how they work for me. I can get decent tones and decent mixes, no problem.
I'm in no way a hi-fi expert, but the headphone amps in my AxeFx II and Scarlett 2i2 seem to work great, with plenty of headroom for both headphones, I have no complaints. Try out what headphones work for you, try some EQ, see what happens.