So dropped in the 1M resitor. Definitely helped.
Spent some time comparing the Jazz with the 490R in my other Les Paul.
In isolation, there's no doubt the Jazz sounds more impressive. It's sparklier, it's broader, it's cleaner, it's more open. Like I said, it has that "wow factor" that I got from the '59. Distorted, it's not bad either. It has that sort of shreddy vibe with lots of pick attack and clarity.
Matched with the JB? That's where it starts getting blurry to me. The 490R has a similar kind of high and low end rolloff that the JB also has. They feel like they "belong together" more. Flipping the switch mid playing feels more seamless. And with some tweaking, it's not hard to make it sound clear and sparkly too.
But then again, the JB/Jazz covers more ground. There's more contrast between positions if I needed that.
I like the Jazz, honestly. Do I love it? Do I like it more than the '59? Do I like it more than the 490R? I don't know yet. I at least don't immediately regret giving it another shot, so there's that.