I do feel slightly called out! It's true I've shied away from testing the headroom before deciding to use my other headphone amp because I was worried about driving the ADI-2 into clipping, but I'm not sure I agree with this entirely.
Since you've replied to me earlier this week, I've tested some songs and the level meters every now and then do come to close to max (even with software ReplayGain & EQ turned on) when there are very deep/low notes playing:
With the exception of the first song, the highest the level meter goes is -2 dB, so definitely not driving in first gear here. Yes, much of the time it is below -10 dB for the entirety of some songs, even with my DSP settings. Again, for most of the music I listen to, the RME works like a charm and gets plenty loud before I even need to push the volume to 0 dBr. It is just that 5% of the time that it simply runs out at 0 dBr. It was the Hans Zimmer music that made me decide to use my SMSL SP200 originally.
- Tsuyoshi Ujiki's "Dry Your Tears BGM" from Hokuto No Ken Soundtrack III (original 1986 CD) hits -9 dB peaks, but 0 dBr is quiet. I have to switch ReplayGain to "track mode" for this song (-1 dB peaks, highest I've ever seen) to become "loud," but not "loud enough," at 0 dBr.
- Tupac's "Hail Mary" from The Don Killuminati (original 1996 CD) hits -7 dB peaks and 0 dBr is just "moderately loud." Same goes for a couple of other songs from this album.
- Michael Jackson's "Thriller" from Thriller (first digital pressing 1982 CD with pre-emphasis) hits -3 dB peaks and 0 dBr is "loud," but not "loud enough" (pre-emphasis removed). Couple of other songs from this album also don't get "loud enough," just "loud."
- Hans Zimmer's "Imperfect Lock" from Interstellar (expanded edition 2020 CD) hits -2 dB peaks and 0 dBr is just not loud enough. Many songs from this album don't get higher than "moderately loud" at 0 dBr while hitting -2 dB peaks.
Again, I apologize for not having SPL data to quantify my subjective claims of loudness, but I take great care of my hearing and would not risk playing at levels that would be fatiguing except for one or two few songs at a time at most. This may or may not be helpful, but here's how I would describe different levels of loudness:
"Loud enough" makes me cringe if it's any more than one or two quick hits in an otherwise quieter song. My headphones sometimes just don't get "loud," let alone "loud enough," especially in the low bass. It's not an issue with my hearing, because I am sensitive to those frequencies when listening to speakers (or even other headphones). As I suspected earlier, I'm not sure the 93 dB/mW specification for these headphones is correct.
- "Quiet" is like overhearing music playing from a phone across from the room
- "Moderate" is like a normal conversation/TV listening level
- "Moderately loud" is an enthusiastic conversation.
- "Loud" is watching a movie or playing music on my speakers at a "fun" level that's tiring after a few minutes
- "Loud enough" is like movie theater loudness, and not really fun except for a few brief moments.
I'm totally the same as you, and feel you 100% here! Thanks for the additional peaks & all info, it's proving very useful since I never had the ADI 1st gen.
I'm doing my best to convince RME to come up with the most comprehensive update lol since I'm positive it's my next 'dream' purchase, so let's make it big and no regrets