This test is harder than you might think. I figured it'd be a piece o' cake with my high-end monitors and treated room. But the differences were often quite subtle.

The -21 db can be a bit tricky to hear. I don't think it helps that the clip begins with a snare. If you don't listen close 
that can throw you off. I listened through ear buds. I missed two when listening to -21 db. Got the rest right.
 
Interesting test, and yes, more difficult than you might think. Maybe the result of hearing pleasant added distortion occasionally added intentionally to tracks for effect.

What??? I've been Zeppelin'd. Sorry.
 

I thought the A test was clean which explains my mixes 

Really well every time a local yoof in his cool, cool wheelz cruisez past.

I'm deaf in one ear and can't hear in the other, it's all the same to me.

All I hear is distortion.
 
And I dinnit even take the test.

bapu
All I hear is distortion.
 
And I dinnit even take the test.

#MeToo...
 
still too soon?

I hear distortion no problem. Crank up some Megadeth or Arch Enemy....

-24db and below were hit and miss for me on my Edirol MA-5A's. Must give it a try on the studio speakers.