This weekend I noticed the quality of sound had suddenly and drastically degraded. I had not changed anything from what I have been doing since 11/1. I also only use AIFF and WAV files. I upgraded to Mojave in mid December ~4 weeks after NI confirmed compatibility and I haven't expericened any issues - I think. Monitors are by Mackie. Headphones are by Pioneer. I usually get decent quality during plays. While trouble shooting, I noticed the sample rate in OS MIDI for the S4 at 48000Hz 8 channel 26-bit. Does 26-bit seem right? Is this the same for others or has something changed in my controller that is causing the lower value on the OS? I restored the OS to an earlier time when their were no noticiable issues with the sound quality but unfortunately, the audio files are kept on a separate drive and had been written over with the new data before I noticed anything. If the issue is from the audio files, then I don't know what there is left other than start over - impossible we are talking 3-4K tracks collecting ~ 15 years. I was using a tag editor to clean up the tags and don't think this could have created the issue, unless this changed the files to something other than wav or aiff. I called Apple Support but didn't get any help. The tech was more worried about the 2018 MacBook Pro speaker issue than trying to help with a possible NI issue. Does anyone have any suggestions or maybe experiencing something similar? I'm hoping there is a solution for my situation.