PS Audio P300, P500 or P1000 Power Plants

Do these Power Plants all sound the same? How do I size the unit? Must I have capacity for the worst case?
I haven't compared them, but common sense tells me that they all sound the same. I bought two P500's rather than one P1000, because they provide more outlets, more isolation, more flexibility and better cooling. The P500 will provide 300 watts continuously, and 500 watts for short durations. If it overheats, it'll shut down until it cools. I have my Cary SLI-80 and CDP running off one P500 and they consume 285 watts continuously. I have my Infinity Intermezzo 2.6 loudspeakers and 1.2s subwoofer running off the other P500 and together they consume 35 watts, even though the three BASH amps together can deliver over 2000 watts. Why is that? Amps use very little of their capacity most of the time, but tube amps are a resistive load and ss amps are a reactive load; and resistive loads are at full power all the time, while reactive loads draw power only as needed. I run one P500 in Tubewave mode, and the other in Sinewave mode; and I can alter the sound by switching modes. It's a good product that makes a big difference in sound quality.
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Good luck.