Well the test (for me) has no right or wrong. If you couldn't tell the difference, then fine. If there are, then fine also. At least you know. And move on.
EDIT (my personal take on the samples posted):
Have you detected something? Yes, on my ears/system, WAV has bit more "weight" (sorry long time in this hobby, but don't know these technical terms), bit more "air" moved? My headphone diaphramn moves more w/ WAV. Seems FLAC is on a two-dimensional plane and w/ WAV they come out a little.
So will you convert to WAV? NO. My existing library? NO. BUT for current/future album purchases if there is a WAV option will choose it (even if there is DSD). But happy on whatever medium the album is available. Usually my preference for online purchases is: 1. WAV 2. DSD 3. FLAC. (no MQA).
So you prefer PCM to DSD? Yes, that is where HQPlayer comes in. Or now that I have now a dedicated format converter/upsampler that takes care of it.
Just MY preferences. Will not debate which is better (if you believe your right then fine -> your experience, NOT mine). Happy on what is available (FLAC, WAV, DSD). Just what I have learned in this journey. BUT always open to discover things. At the end its all about MUSIC.