The REl Stadium II has a 180 phase reversal switch. On mine I spent a lot of time trying to dial the sub in & the owners manual said to try reversing the phase if all else fails & that did the trick. I have a friend who is a bass freak & he asked If I could reverse the phase & when I replied in the affirmative he asked me to do so. I didn't tell him I had the phase reversed. After several songs & switching back & forth He stated He liked the original setting. He was surprised when I told him it was reversed. REL just came out with a Stadium III so you might be able to get a deal on a II. You can get adjustable crossovers with a lot of subs but for phase I think your options are in or 180 degrees out.The REL even though it is self powered is connected to your amp & has a gain contol & fine & coarse filters to blend it in with your system.There is also an extra input for surround sound system.I have had B&W & Mirage subs in my system & I sold both because I couldn't get them to sonically mesh with the Logans. I am very happy with the REL whether lisening to music or watching movies. Good Luck !
