The wall mount may well have an influence Doug, but I can confirm that your P3s seemed no more in need of a sub than my own PMC 20.21 (though that may not be the best comparison for you PP, as the 20 was your least favourite PMC range if I recall correctly).
I think a relevant point is that I listened to Doug's speakers at what I describe as a realistic volume level (and by that I don't mean excessively loud).
But I do remember you mentioning on the Wam, that at one point during your tests, you had to raise your voice to converse with Lady Penguin. That surprised me.
You see, there's just no way that conversation would be possible in the same room as music at my normal listening level.
I could be wrong, but I think the difference in (usual) listening levels, may go some way to explaining why you think the P3s need a sub, whereas Doug and I don't.
Of course, smaller speakers will always have bass limitations. There's no doubt that a sub would (partially) act like an amp's loudness contour to help low level listening on most small speakers.
I do appreciate the benefit of bass (in my work, I've heard bass bin stacks that make domestic subs sound like transistor radios).
But my neighbours would be sure that my small speakers don't need a sub
.