For anything audio quality related you need audio analyser. Or audio card and software.
12 bit scopes cannot verify 16bit audio, not to mention 24bit, except for large distortions...
From what I can see all you need is 4 ch, even for digital. No need for MSO.
MSO is really useful when you NEED 20 channels.
Avoid HDO924. Horribly designed device.
Stick with HDO800 or Siglent SDS800 HD(my choice).