The test isn't new -- it's been on the Tidal site since last year. We're suspecting it hasn't been updated since (hence the "prize" of half as much free trial). The challenge pits a 1,411 kbps lossless / FLAC version of a song against a 320 kbps AAC copy, you simply choose which one sounds best. When the Engadget team took the test, our results varied from 2- to 5/5. I got 3/5 -- slightly better than guessing-- or given the odd number of choices, I was lucky on one of them. I re-ran the test and got 5/5 by simply swapping the two choices I got wrong (this only works some of the time).
Perhaps it's the timing (look at the date), but ironically, this test could steer people to the lower cost service if they struggle to tell the difference. After all, why pay more? If you find out you do have golden ears (or just good luck), will it be enough to to make you pony up? This group of people ripe for conversion seems potentially small. Especially as most people that want a non-compressed service will already have made that decision -- they don't need a test to convince them.
Take the test for yourself, and see how you do. Right now, it feels like the punchline to a terrible joke: first prize? Two week's supply of our product. Second prize? FOUR week's supply...
(Update: and just like that, the test has been updated. You can now win the same 30 days trial that you can get just by signing up)