I have little-to-no FOMO. I’m happy with my EQ’d 6XX. I know there are objectively better headphones, and I’m sure that there are headphones that would be subjectively better for me. But they sound fantastic. If I wanted to spend a grand auditioning similar headphones or springing for the next tier, I’d rather get a new fork for my mountain bike instead.

iPhones will report this, at least with Airpods and presumably Beats. It’s in Control Center -> Hearing. They know the sensitivity of their own devices, so they can calculate the loudness. I have also seen this in screenshots of at least one the third party phone apps that many headphones come with.

Too damn loud. 95dBA especially. Why louder for the gym? If it’s because of a noisy environment, I strongly recommend getting noise cancelling. The cost is negligible. You will rely on your hearing all your life, so don’t mess with it.

I can’t find a reference to its output impedance. Seems very unlikely since the amp will likely be paired with hifiman’s low impedance planars.

I wouldn’t recommend the Cobalt if you don’t have anything yet. If you already have the Cobalt, try it and don’t worry about it if it works for you.

Cobalt has very low noise but relatively high distortion. But the emphasis is on “relative.” Most of us don’t hear the levels of distortion that the Cobalt generates at normal listening levels. It’s still way less than 2% THD, and still way less distortion than some pricey tube setups. You may even prefer that distortion. So again, listen to it loud and decide for yourself if it sounds good.

The other issue is that the Cobalt provides about 14mW of clean-ish power. That’s enough to drive the 800S to a standard 110dB target. But those cans have rolled off lower bass. If you want to use EQ to juice the bass, you might run out of power. Same if you listen to quiet recordings without software gain adjustment.

For me, about six months in the pads are way more comfortable than new. They’re a little tough at first, especially with glasses. They soften up over time. A little too quickly for some I surmise.

For learning how to differentiate different kinds of distortion, Harman has an app called How to Listen. You might have to change the sample rate fed to the DAC for it to work though.

A really intuitive interface (with good keyboard support) for listening to differences in lossy codex is found here.

If you want to differentiate between different sonic profiles, download Equalizer APO, put in a bunch of profiles from autoeq.app, and toggle between them to your heart’s content.