Replaced the J100 in the neck of my SDK-075 with a Duncan stacked single (STK 4N) that I scored off eBay. Thought it might have had an issue as there was very little output but after some cursing and testing it turns out the 5-way switch post for the neck position is toast. Or rather melted plastic.
So, I set the neck up for middle switching until the new 5-way comes in.
Impressions: Exactly the tone I was hoping for, meaty and throaty with some nice clarity. Doesn't get all muddy on the lower register. 60cycle hum is gone. Output is more than the J100, better balanced to the J90C bridge humbucker. I may see if I can't get something for the neglected middle position down the road a piece.
