I just got a p5 desktop as well and, although the oscillators are very much in tune, I can't say the same about the filters. Setting the filter with full resonance, no oscillator input, FULL KB, and tuning A4 to 440Hz, results in something that's way off tune.
Is this supposed to get better over time with more runs of calibration, or does it need internal adjustments ?
[edit] I'm an idiot. Setting the Vintage Knob to 0 fixed it immediately.