My first thought when I started reading this thread - you cleaned and therefore removed the factory lube between the pins and rollers. The toughest place to get your lube into. (Hence the repeat the lube several times after cleaning advice.) The two chains had different levels of lube furthest from the lubing location, hence the sound difference.

I am not a fan of cleaning chains in solvents unless I am switching to a different lube system that is incompatible. (The plastic based lube whose name I have forgotten, wax ...) The Finish Line wet MTB lube for my commuters and Tri Flo for my good bikes works just fine with the factory grease. I'm not obsessed with squeaky clean drivetrains so perhaps most here need to ignore my comments.