You are right. Beats is way more than just a gimmick on the HTC one.
It's not a gimmick, but IMO it is more or less just amplified and bass heavy.
No, the headphones do not simulate the experience you get with the built in software. They are just pricey headphones with a name brand. Try skull candy with HTC one.
I have been using Volume + for years and I am happy with it.
It has an EQ and a volume booster if needed.
Link for Volume + at the play store.
https://play.google.com/store/apps/details?id=com.TEST.android.lvh&hl=en
I read the reviews from Nexus 5 owners. Both gave it one star. Are u using it for the N5?
i had been using dsp manager, it was an improvement, but last night i tried viper4android and fell in love with it, even better than beats audio since it is highly configurable yet very easy to adjust everything to how you want it, just spend 10 minute messing with the settings and you'll forget all about beats audio
I played around with PowerAmp a little and got it to sound a much better. Still thinning about using my One X as my main music player. Hopefully google can put out an update to help enhance music for this device.
I came from a One X too and I am in the same boat as you man. I love the Beats Audio software and used to think it was a gimmick until my friend got one before me and we tested it. Not only is the bass deeper but the sound is richer and louder. If you're rooted you can load the software on your N5, but its PERMANENT. Or you could flash a ROM that uses the software.