Like DaGaff, I come from humble JBL beginnings.4311's,L100's at home,others.....they are wattage sponges.No matter what the rated wattage, they can always use a bit more.I had mine hooked up to various high gain high slew rate amps and these are what produce the best results with them.Without spending a crapload of ducats on a new set of monitors, you are not going to find a lot of quality difference in most from your JBL's.If your amp is substandard, I would look at this as a possible great improvement in your sound.
For the first poster,theres a huge difference in size and style of monitor between the 4410 and the little Yamahas.Like Gaff said, you need a big room for those 4410's.....and a big power amp.