I have both the PRS Custom 20 combo and the 65 Princeton Reverb Reissue, and both amps are stock. I love the PRS amp, but my Princeton is my favorite. I play only around the house, and I tend to spend the most time with a clean setting. I have many pedals that work very well with both amps: KTR, King of Tone, OCD, Rat, Plimsol, Tumnus Deluxe, D&M Drive, EP Booster, SL Drive, Bonsai and Muffuletta. I mention the pedals because you may have some/all and know what you like.
I play Gibson Les Paul, Fender Strat (SSS), Collings I-35 Deluxe, Fender Tele, PRS Silver Sky, PRS Custom 24 and PRS McCarty 594 and both amps like all these guitars. None have P90s, all the pickups are stock.
I love the spring reverb in the Princeton, and the tremolo too, but the reverb really pushes my buttons like nothing else I’ve ever played through. I bought a Boss ‘63 Fender Reverb pedal to use with the PRS amp because the PRS spring reverb is too transparent for my taste. The pedal is on all the time with the internal reverb off when I use the PRS amp, except when I use the drive channel I turn both off. The pedal does a good job of sounding like the Princeton spring reverb, but it is not a direct match. It is said that the 68 silver face Princeton Reverb takes pedals better than the 65 because it has less negative feedback and breaks into overdrive easier. I prefer the 65 black face and think it takes pedals just fine.
I’ll never part with my Princeton, unless it is to replace it with the 64 hand wired version.