Hifiman HE-5XX but with a little more bass? Suggestions?

I’m fairly new into the hifi/audiophile community so hopefully I can describe what I’m looking for without pissing people off. The HE-5XXs were my first open-back and planar headphones, and to be honest I love almost everything about them. The openness and clarity is awesome in my opinion. My only gripe about them is I wish they had more bass, and that I can crank them up louder. I have a ifi zen dac (pretty sure it’s the first version) with power match and truebass turned on. My zen dac is feeding(RCA Unbalanced) into a loxjie p20 with JAN GE 5670W / 2C51W tubes that outputs to my HE-5XXs. I usually keep the loxjie set to max volume and control the volume with my zen dac and at about 40/50%-ish on the zen dac’s volume wheel the HE-5XXs starts peaking, getting distorted, poppy, fuzzy sounding, especially with more bassy music but they’re still not loud enough for my preference(I like it loud). Also should mention I use HE-5XX eq profile by oratory1990 on peace. Maybe my setup isn’t adequate for what I’m trying to get out of the HE-5XXs? Maybe the HE-5XXs aren’t meant to be pushed that far? Maybe I’m doing something wrong? Looking for any tips, setup suggestions, headphone suggestions similar to the 5XXs but better fit my preferences, input on things I should be doing differently, anything, even criticism.

P.S. Thank you in advanced, and sorry if I was to specific or not specific enough in decribing everything, I tried to be to the point with as much detail as I possibly could for better input.

Edit: I mainly use my DT1770 Pros since I can’t get the loudness I want out of the 5XXs. I also sometimes alternate in my pair of Monoprice modern retros when I’m on a bass kick. I really love the sound signature of my 1770s(they were my first pair of hifi cans) even though a lot of people seem to not recommend them, because they’re harsh at times, but I like that. The bass is perfect and they go way louder than what i’m comfortable with. I’m just torn because I want the same characteristics but open-back, I really fell in love with the openness when I tried the 5XXs.

haven’t heard the 5xx personally but I think the Hifiman edition XS is one of their bassier headphones, maybe the Ananda Nano

Setting the zen dac to fixed output and using the p20 volume knob instead could help with the distortion and clipping issues.

The balanced connection can also get you significantly more volume. This interconnect should work to connect the zen dacs balanced output to the p20 balanced input. You’ll also need a balanced headphone cable as well.