I've tried just about every EQ on the market and really like EMG's 2-band for the John Kahn tone. Reminds me a lot of the Sadowsky preamp, which I do prefer but costs about 3x as much and takes a little soldering whereas the EMG system just plugs right in. And let's face it I'm a little lazy! I used it in my Steinberger for cost and space and ended up really liking it and putting one in the black P too.
My 2nd most played P has an ACG EQ-02, a really awesome system, that does an even better Phil. But I prefer the bridge pickup and the neck itself on the black and white above. If I was really building a Phil P I'd use a soapbar of some sort in the neck and an ACG. http://www.bestbassgear.com/acg-eq-02-preamp.htm