17th June 2008
Lives for gear
It will depend on whether there is a 24bit path anywhere (TDM or PowerCore) and whether it is dithered. It will also depend on how you reduce the level before the recording (at 24bits) and whether the gain reducer provides dither.
The worst that should happen (even if there are 24bit paths) is that the noise will increase - potentially to -100dB from -140dB or so, all else remaining the same.
The worst that could happen (if there are 24bit paths that are not dithered - i.e. your recording file) is that you will have signal dependent distortion at -100dB - which may reduce your sound quality.
Reducing level by 40dB before the ADC in the analogue domain is a different matter entirely.
In this case the ADC noise (maybe at around -110dB) will increase to around -70dB when you bring it back up in the digital domain - which is quite a bit and not advisable.
But having said that, the actual signal quality in terms of distortion will probably be unaffected with modern ADCs.
And as a very final twist - if you have lots of ADC noise and your W/S has undithered signals (either at the recording file, in the mixer or plugs) - and you don't care too much about noise in a loud (rock) production - it is possible that the ADC noise will dither those signals and it could actually end up sounding better, despite the extra noise.
I hope this helps.