I would rank SQ as 1) PXC 550, 2) MM 550, 3) QC35, 4) QC20. It is great for the price! I have this on a 12 chain and 100 of rope for a 19 boat, for which it is technically oversized, but works great. It became so painful that I had to stop wearing them altogether. Got the size 6 and though its a tiny bit wide, its good. Turning noise cancelling without anything playing muffles the sound from the outside, it doesnt cancels it completely, but once you turn on some music, even at mid volumes, kids playing-level noises get shushed out. Im going to try and see if it gets better before my return date comes. Hard to get the earbuds to stay paired to the phone. Erfüllt seinen Zweck, klare Töne, rauscht nicht. " All made clear on the website, with charts!