Tarah Pro has a noticeably quieter max volume than my old earbuds (this is a bad thing)

I bought these to replace a cheap pair of Skullcandy earbuds I had bought about 4 years ago that I was reasonably happy with that broke. The Jarah Pros were several times the price, sounded worse, and my biggest issue perhaps was that the max volume is considerably lower on these than my old earbuds.

Using:
- iPhone 7
- Spotify
- Youtube

Settings:
- Usual volume control at max (earbuds appear to be in sync with phone)
- Spotify settings at loudest
- EQs... tried any number of EQs on both Spotify and via the Jaybird app
- iOS Limit volume setting turned OFF
- iOS max volume set to max 

It's still wayyy too quiet and genuinely sounds bad. The behavior is consistent across both Spotify, Youtube, and anything else I play off the phone into the headphones. I don't have this issue on any other Bluetooth device that I use with my phone. Every time I used them I had to have the volume pinned to the max just to get to a halfway enjoyable level and they still weren't anywhere near close to loud enough. 

Is there any logic or mechanism in the headphones themselves that is limiting the volume? If so how do I disable it? Is there a setting that I'm missing somewhere? I knew I was going to return these the moment I saw that there was a proprietary charging cable so this is all for my own sanity.