My personal opinion is that the number of watts isn't always a true indicator of quality. I believe that an amplifiers ability to handle high current loads (i.e. low ohms) is more important. I recently stepped up from a Onkyo receiver that was rated for 90 watts per channel and a 6 ohm load to an Integra receiver that is rated for 135 watts per channel and a 4 ohm load. My Focal speakers have an 8 ohm nominal impedance, but have a low impedance of under under 3 ohms (I believe). High watts is only required at higher volumes. As long as you can get the volume that you're looking for you should be fine as long as the amplifier has adequate current handling capacity.
The Denon is a more 2 channel specific design which could allow it to sound significantly better, but nothings a given. The more simple the design of the amplifier the less things there are to degrade the signal.
You could use the pre-outs on the Marantz and run them into the Denon, I think, and just use the Denon as an amplifier. I'd consider packing up the Marantz and taking it to the store for a side by side comparison.
I say get the Denon IF you were considering a straight swap, but I doubt the addition of another component would be worth the additional cost and inconvience of having one more component. Marantz is a very respected name and they have quality products. I'd suspect it might sound more different than better/worse.
The Denon is a more 2 channel specific design which could allow it to sound significantly better, but nothings a given. The more simple the design of the amplifier the less things there are to degrade the signal.
You could use the pre-outs on the Marantz and run them into the Denon, I think, and just use the Denon as an amplifier. I'd consider packing up the Marantz and taking it to the store for a side by side comparison.
I say get the Denon IF you were considering a straight swap, but I doubt the addition of another component would be worth the additional cost and inconvience of having one more component. Marantz is a very respected name and they have quality products. I'd suspect it might sound more different than better/worse.