hey compellor, i had the SAME experience. i bought a wbk38 with the delta 38cfm fan in a package deal in the fs/ft forums. before i even got it i also bought the 23cfm 60mm sunon fan from someone else in anticipation of replacing the delta. well, i started off with the delta and immediately planned on selling it. i tried out the sunon and the performance, while good for its volume, was nowhere near the delta. i keep my case on my desk, literally 1 foot from my head when i am by my desk and 2 feet from my head when i'm in bed. with the side of my sx830 case on and the 5 80mm case fans going strong, after a while the whine of the delta fades into the background. i guess it's also because there is a ~7 degree difference between the 2 fans on my 1.33 t-bird @ 1.54 at 1.85 volts.