A couple months ago I had decided to build a new partscaster in a 50s vintage Strat style, got some great parts and put it all together, fantastic guitar except of course for that Strat single coil hum--especially in my home, where the wiring is old and leaves a lot to be desired. Before I installed the Bzzzzkill Dual Layer (the Strat is loaded with V-Mod II RWRP pickup set, as the body I got came with them, and as an aside I also was pleasantly surprised at how good those pickups actually sound), I did a quick and dirty little recording, just some cowboy chords, clean and dirty in all pickup selector positions.
After installation, which was a breeze, I metered the pickup outputs to find the DCR had gone up by about 4k for all pickups, basically expected. And the hum was completely gone on clean settings (amp is a Fillmore 25), and decreased so much on the drive channel settings, so quiet. The RWRP positions still canceled hum completely, no matter what. The true test would come after recording the After--and I'm super pleased to report that the differences are minimal at best. From the recordings with same amp settings, same day, same recording setup, to my ear there is a slight bit more fullness in the mids, but the treble seems to be pretty intact, the volume is about the same, the lows are still there, the dynamics.
Highly recommended!