I've heard the Polks and I have pair of M22s. I haven't heard them side by side but it didn't take a side by side comparison to tell that the Polks sounded veiled and uninvolving. I felt that the upper mids and highs were rolled off and upper bass sounded bloated. I didn't hate the Polks, they just weren't my cup of tea. YMMV.
IMO, the M22s have a more brilliant sound (not to be confused with "bright" or "metalic" *Curtis*
). With the M22s it's all there, nothing is rolled off except the bottom octaves which is to be expected from any bookshelf speaker. But what is there is very well balanced and no frequencies are emphasized over others. That balance is what I love about the M22s.
Of course this is just my opinion and what sounds veiled/rolled off to me may sound delightful to someone else.
