Different speakers with different sound signatures and different efficiencies in different placement... the entire system has changed so of course it's fair to think that amplifier power requirements would be different. Bottom line is that if he's achieving satisfactory volume levels then the number showing on the receiver is irrelevant.So I got a new HCS S809 Jamo speaker 5.1 setup with the S810 sub as a gift for my dad to replace his Bose Acoustimass 10 Series V system. After everything was hooked up and some movie watching, he noticed that he'd have to turn the volume way up more than he did with the bose. The bose sounded louder and clearer at low volume. On the volume scale 0-100..he'd have it more around 40 for regular listening and 50 would be really loud. On this new system, he'd have to get it up to 70 for it to sound loud. Can anyone explain what's happening?