Priz, a couple of things that you mention that you're "sure" of are highly unlikely. First, if your present Sony is rated at 110 watts per channel, you can be confident that it would actually deliver that at maximum output. As we discussed earlier this year, that rating has to be met in a lab test(no home audio use is this severe)for at least five minutes continuously under FTC regulations which apply to all receivers sold in the U.S. Failing to meet the advertised power rating would be a violation of the law and manufacturers aren't foolish enough to do it. This is confirmed by AV magazine lab tests on the units in question.
Next, if your Sony is operating within its designed power limits it's amplifying the entire audible frequency flat and with inaudibly low noise and distortion. This is all that any amplifier can do(sound processing is a separate matter)and there's no good reason to expect better sound from the Marantz unit.
As to the power ratings involved, keep in mind that at a comfortably loud average listening level your speakers will be using no more than about 1 watt. Brief peaks use much more, of course, depending on how wide the dynamic range of the material being played is. The difference between 80 watts and 110 watts is only about 1.4 dB in maximum sound level possible at peaks, for example 106.4 dB compared to 105 dB. It's unlikely that the difference would be significant in your use, so if the 4002 has the features that you want, you shouldn't hesitate because of the power rating. I'd agree however that the the new Onkyo 705 would be an excellent candidate and should be considered.
