Hi,
I have the A324 and as Hantra said, it smoked Mensa at a DAC shootout at my house.
How does the P3A stackup. I would have to say that it doesn't. I've heard the regular P3A and a modded P3A. In both cases I preferred the A324, however the modded P3A was very good.
After hearing probably one of the DACs on the planet last night, I can say that there isn't much room for improvement on the DAC side. Both Hantra and I have heard this same DAC. That being the Accuphase 101. In CD mode, I couldn't tell much of a benefit over the A324. In SACD mode, with a good recorded SACD, there was no comparison, albeit my vinyl is more enjoyable to listen to.

To this date, the most enjoyable CD Player I have heard in my system, was the Audio Aero Capitole MKII.
So, the moral of the story is to look elsewhere for improvements.
The room being by far, the place to yield the biggest benefits and free to experiment.
Have a great day,
Brad