OP-1 Line In Input Gain "Unity"

I’m not sure if “unity” is the right term here, but I’m trying to understand why when I record with line in it is way quieter than what I am expecting and I always have to boost the signal to like +25db in order to get it to match what I am recording.

I am aware of the radio input gain bug and I guess it could be that (even though I am on firmware 242) but I set that to +0.0 and it’s still really quiet.

Can anyone explain what “unity” is supposed to be? Is it +0.0. That would make sense to me but that’s definitely not the case for me. I don’t think it has to do with the recording input level as I have that to about 80% (the default).

To test this I did the following:

  • Opened a song in Audacity and took note of the loudness by listening and the vu meter.
  • Connected my MacBook headphone out to line in of OP-1 and set volume of MacBook to 100% (this is really loud if listening to headphones).
  • Set line in volume to what I thought would be “unity” (+0.0) and recorded to track 1.

When I compare the original audio file in Audacity with the track_1.aif by opening them both in Audacity, it is way louder so it seems that some kind of attenuation is going in the OP-1. I’m not sure if you just need to record higher than +0.0 (again I thought this was unity)? I assumed that going above 0.0 would amplify the signal.