Should I unfreeze tracks in ableton before exporting a song? Just wondering if this will make any difference in the way it sounds. In the past I noticed when I exported songs with tracks frozen they didn't sound as good but it could have been some sort of placebo effect. I think I might have been playing around with the sample rate too so that could have been a problem.
Whether a track is frozen or unfrozen in Ableton shouldn't make a difference in terms of audio quality but might make a difference in terms of audio content. The reason for this is that you might have modulations in your track that are complex enough that each time you play the track, the result is slightly different. When you freeze a track, you capture a particular set of modulations. That set of modulations might sound better or worse than the last one you listened to.
I assume that when you freeze and flatten a track, the resulting audio is at the project rate. If your project rate is 96 KHz and your export rate is 192 KHz as in your previous question then you may notice a difference between the quality of the unfrozen track and the frozen track. I'm making an assumption here that the frozen/flattened track will be sampled at the project rate, rather than the export rate.
When I freeze a track, I usually start by duplicating the original track. Then I freeze the new track, and then flatten the new track. Finally, I mute the original track. This gives me the original material and modulations used to create the audio file, plus a static audio file that is both easy on the CPU and captures that particular set of modulations.
You can take this a step further and export two versions of your track - one with frozen tracks, and one without. Then create a new Ableton project, and drop the two tracks into two different Audio tracks. Turn on the crossfader, and enable one track for the A side of the crossfader and another for the B side. Slide the fader all the way to the A side, and launch both clips at the same time. As your tracks play, move the fader back and forth. Can you tell a difference? Is one better or worse?