First and for most. I Would like to say thanks for all the responses.
Shady, could you elaborate which one is better?
Could one ported sub defeat two subwoofers in a sealed configuration?
This comment is leaving me kinda skeptical on my purchase.
I think that the F25 is a higher performing subwoofer, by virtue of having two drivers. The F15HP has a single driver (the DS1510) which is higher performing than the F25 drivers individually (the DS1501), but it won't outperform two of them together.
A ported sub, for example, the FV15HP, can outperform the F25 at its tuning point, but probably not above 40 Hz or under 12 Hz, so the FV15HP gives you an advantage in a narrow band, but an important bad for movies although not so much for music. If this sub is for music alone, and the music you listen to is regular acoustic recordings (ie not the forms of electronic or organ music which actually dig very deep), a sealed sub like the F25 should do fine.