Can anyone please tell me what the difference in specs between the Bowers & Wilkins ASW 850 & ASW 875 is? Is it significant and worth upgrading to the 875 even if I could get an amazing deal on the 850? As far as aesthetics, has the design been refined in any ways? What do you gusy think and given that I could get a very good price on the 850, what would you do if you were in my position? Sound quality is obviously the number one factor for me so even for a great bargain, I'd rather not sacrifice quality if it's significant for a deal. However if it's basically the same sub with little difference, I'd jump at the 850. Please offer opinions/suggestions... Thanks!