where i found it: before i was born
I've been on a jazz piano jag as of late, getting mostly into that great spot, mostly between 1955 and 1965, when the line to traditional chord changes was fraying, but before it popped and hurled everyone thrashing into the atonal abyss. Some of my favorites from this time are the early Cecil Taylor records before he became a mad genius shrew and way before he only had one dreadlock left and started bringing bags of groceries on stage. Monk is still solidly there in his playing and classical runs are fully intact, but his expressionistic spasms start to peek through and - for me - they seem exceedingly fantastic in this context. Not to mention Steve Lacy, Dennis Charles and vibes player Earl Griffith walking the same tightrope in their own virtuosic ways. You can get this stuff for cheap via amazon and the Real Gone label, but it's not so hard to find on vinyl if you're willing to do a tiny bit of hunting.
Along the same lines, but slightly more reigned in in terms of tonality, I also can't help but to mention the great Lennie Tristano and his New Tristano record. I'm not going to say much. You should just listen.