ranking instruments from quietest to loudest

[Lopyt]

If you want to do this scientifically, take a recording of every sample for every instrument and put it through a loudness analyzer, then you can see which instruments have a higher average loudness. Use LUFS-I as it analyzes the entire audio file and not just a small section like LUFS-S.

For db you can put them all through a peak meter and see which one has the highest reading in db