Here is a sound sample of a P-90 pickup. The first 2:17 is
a PRS SE soapbar II going through a Hughes and Kettner Duotone 100 watt head. The cab has celestian V25's in them. One sm57 center of the cone, no effects, no eq, no bells or whistles just pure tube tone. A smidge of compression to bring up the volume of the track.
I start out with low gain settings, use palm muting and ringing out chords, then just play the same thing each time turning the gain up little more on the amp.
I guess if I had one word to describe a P-90 it would be "ROBUST", or "PUNCHY", or "JANGLEY". OK thats 3 words. Great for leads and chords and insanely full sounding on a clean amp setting.
This was a one taker. The second half which is more metal sounding is a Duncan JB humbucker with the amps gain setting close to maxing out so at least you can hear a difference in sounds between two pickups.
hope this helps.