Here's an AI take on the issue. Bear in mind that AI is not always 100% accurate...
"SoundTap is very likely causing Amazon Music to lower its playback quality to 16 bit / 44.1 kHz during recording, meaning the captured audio is throttled to a lower fidelity signal regardless of the file output settings in SoundTap. The file created may still be tagged as 24-bit / 96 kHz simply because that's the recording format you've set in SoundTap, but the underlying audio signal is only as high-fidelity as the stream coming from Amazon Music at the time of recording.
How SoundTap Affects Fidelity
When SoundTap records audio, it intercepts the output stream from the app or OS. Many streaming apps, including Amazon Music, will reduce audio fidelity when they detect recording software, often as a DRM measure or due to how audio routing changes. The effective quality of the recording is determined by what is actually played, not what SoundTap is set to record.
Amazon Music “Currently Playing At” Changes
Amazon Music typically adjusts its playback sample rate and bit depth based on both device capabilities and any intervening software. Recording software like SoundTap can force Amazon Music to downsample the audio to a lower rate (such as 16/44.1), regardless of your Mac mini’s hardware capability of 24/96. This means your recording may always capture the lower-fidelity stream even if SoundTap saves at a higher format.
File Format vs. Signal Quality
Setting SoundTap to save files as 24-bit / 96 kHz does not improve the actual audio if it is intercepted at 16/44.1—the file will simply have empty bits and upsampled data with no real increase in detail or quality.
Recommendations
To maximize fidelity, manually set the output device’s sample rate in your Mac’s Audio MIDI Setup before playback, and check if Amazon Music “currently playing at” matches your target rate.
Beware that most recording tools, especially those that capture system audio, cannot override what Amazon Music is willing to output when recording is detected.
For true high-fidelity archival, seek solutions that do not trigger Amazon Music to throttle playback, or use an external digital recorder if possible."