Shared Mode does not affect recording and playing while Exclusive Mode is enabled.
Which two hosts are you referring to? Audacity disregards Exclusive Mode in MME host, so it will always use whatever setting Default Format is. The other two hosts (Windows DirectSound and WASAPI) respect Exclusive Mode, most completely so for WASAPI.
For the test mentioned before, here is more details:
- “Exclusive Mode” is disabled in Windows Sound (the two boxes are unchecked)
- “Shared Mode” = 16 bits, 44100 Hz
- The sound file is in 32 bit float, 48000 Hz generated with Audacity in “Generate → Tone”:
- Waveform: Sawtooth
- Frequency: 23000 Hz
When playing the sound file in Audacity or in Windows Media Player if Audacity is recording:
- MME: OK
- Windows DirectSound: same problem as VLC, the sound squeaks/crunches a little
- WASAPI: OK