I just wanted to chime in . I owned two 505 s corner loaded for a few years and then found a reference on Craig's for 535 in mint cond. For that price it was a no brainer. I can't do a direct a b between the two subs since the reference is in a different house but the room is twice as big and it smokes the two 505s. It does dig deep also and has a much cleaner sound through the freq range. It is much more musical/tighter than the Polks to me.
Harmony Elite, UN65F9000 with SEK-3500, Denon 3808CI, Denon 2500BTCI, HR54-500, C51-100, C61K-700, Xbox 360, Chromecast 2.0, Mythos ST, Mythos Ten, Mythos Gem XL, Supercube Reference, Belkin PF60, Tartan and Monoprice cables, Zone 2/3 AW5500.