I'm still confused about your position. You seem to be very biased about wanting lower distortion at max output levels. However, you say you'd choose the pb13 for deep frequencies, but yet it has higher avg distortion below 20hz. Conversely, you'd choose the fv15hp because you prefer 25hz and above, but it has higher distortion compared to the pb13 above 25hz?
I am pushing for lower distortion at deep frequencies, because distortion is so easily discerned down there.
The PB13 has more distortion as a percentage of its deep frequency output, yes, BUT where it's deep bass distortion takes off, its output drops off swiftly, so you don't really hear much. The same is not true for the FV15HP, it has a big spike of third harmonic distortion surrounding 20 Hz where it still has a lot of output, and it happens in both ported operation modes as well. As far as above 25 hz goes, neither sub can really be pushed past 10% THD over 30 Hz and even then it is mostly second harmonic, so they are nearly even in that respect. I would only take the FV15HP over the PB13 here for its slight upper bass advantage, but it isn't very significant. It's more a matter of the money I would save if I were thinking about buying one. Hopefully that explains my reasoning a little better for you.