I cant speak for the Polk 505 as I have never had the chance to listen/feel it in person but for $170 at NewEgg it seems to be a good price! I can however comment on Premier Acoustic as I own the PA-150, its a fantastic sub!! I use to have dual Bic Pl-200's as I replaced them with the PA-150 and couldnt be hapier... esp for $370 shipped. I do realise the 150 is much bigger than the 120 but just going by build quality there is quite a bit of differnace. Dont get me wrong, the Bic Pl-200's are a very good sub as it did well for HT. Hard to say about the Polk but IMHO I would put the Pa-120 over the F-12.