...quick check on my JBL 305P (garage speakers), ATH-MX50's and QC25s. .
Note, I usually don't listen very loud but have never measured average at MLP so I can't given a #.
305Ps - Using pink noise using a dB measuring app on the phone. Get's just as loud on the headphone jack as dongle (that I'm happy with, not Apple which was too quiet). Way louder that what I need/want, but those are background while wrenching so listening levels are usually quite low.
ATH-M50X, borderline loud enough even all the way up.
QC25, also borderline loud enough. Maybe a bit louder than the ATH-M50x but I won't hang my hat on that. It's more that I can listen to the M50X all of the way up but it's bothersome on the QC50's. Very well could be some other issue like frequency response or distortion.
Both I'm only a notch or 3 below full volume to be where I normally like to listen.
IIRC both of these aren't terribly hard to drive headphones and I don't listen at loud levels normally. So unless there's a defeatable SW limiter that's causing this, I wouldn't be surprised if this doesn't have enough oomph for many people's situations.
It will be interesting to see if this get's measured somewhere and/or on a broader scale what happens with the SW limiter due to new dB limit regulations.
Other, Wavelet seems like it's not working, not doing anything both through the headphone jack and USB (USB>Schit Mod2>Vali2). As a sanity/ears check I got the Pixel3 back out and Wavelet definitely works on there.
Edit, maybe fixed? I had it in Legacy Mode, which didn't seem to cause issues on the Pixle 3, but caused it to not work on the 5a. But now I can go into either mode on the 5a and it works fine.