Some folks have noticed that they can't set their rear speakers to large with no sub fitted. Obviously without a sub, you need to make sure the amp sends the all the bass output to the speakers. Richer Sounds agreed to replace mine but when I went to collect the new one today, I made sure they tested it before it left the store. It was the same as my old one. Some SR4300 owners here on the forum have confirmed the same problem while others have said that theirs were fine. It seems like earlier models are fine but later ones have the bug. Marantz UK confirmed they have heard of the problem but were a bit vague. After a bit of negotiating, RS agreed to swap out with a SR5300 for an additional £50. As I only paid £229 for the SR4300 in the first place, I think I got a good deal. I'm not an audiophile and I was really impressed with the SR4300. I didn't think I'd notice any improvement with the SR5300 but I reckon I can tell the difference. Perhaps I'm trying to justify the extra dosh I've read a few bad things about RS's after sales service but I have to say that my local branch in Norwich have been very helpful every time I visit.