This is an old post but I am responding to it as I am still using my LP1. I did modify mine to it is now singled ended from a +30Vdc supply, rather than the +/- 15Vdc. That meant putting polypropylene caps on the output to block the DC. The design did add significant bass impact as it eliminated the sensitivity of the op amp to noise on the negative rail.
Definitely use polystyrene caps on the upper pass region.