but not real happy i think my speakers is never reaching full peak speakers at 100W 8oms but receiver is 75w 8oms.
The speakers don't have a "full peak". That's just an arbritrary rating. THe difference between 100w, and 75w, is 2.2 decibels. In fact, I addressed this exact confusion about amp/receiver matching in this thread of mine:
http://forums.audioholics.com/forums/showthread.php?t=75823
so heat is a consern also when picking out a new receive
All receivers will produce heat. You need to have adequate ventilation, no matter what.
thinking i prob want to try to reuse the speakers that i have now,
Don't expect to get much upgrade in sound quality from adding a new receiever. You might get some small increases in output but nothing memorable. Your audition at best buy was not indicative of what you'll be experiencing IRL. IRL, you wouldn't be able to tell the difference between any of those receivers in source direct mode at the same SPL.
It will make a big difference dont see how it will not at this time.
And adding a new remote control will make movies so much clearer, and upgrading from a PS3 to a PS3 slim will make gaming so much better.... oh... wait...
Look, I'm not saying not to get a new receiver if you need modern features, but if you want to improve your sound quality, here's five tips I'll give you
1) Do things to the room in order to clean up bass response. Bass, and small rooms, are not friendly with each other. Thick bass traps along corners are a place to start, right while you're still designing the room.
2) Do things to the room in order to improve spectral balance and decay as desired. The room is a big part in what you hear, so adding things like well placed reflection, absorption, and diffusion will make a bigger difference than a receiver will. Floor, ceiling, front wall, back wall, side walls, it really helps to figure out what is appropriate to get the room sounding its best at the SPLs you listen at, to the content you listen to. You mentioned you are more of a movie guy, so you might have an inclination to a more dead room. Movies are mixed for an RT60 around 300ms, and most rooms have an RT60 around 500 to 600ms, so you've got your work cut out for you but luckily you're still in the room construction process if i read it correctly.
3) Get better speakers - better measuring, better sounding, more sensitive, better power handling, whatever it is, better. Whatever suits your situation, we can help you figure that out when you get to it.
4) If you're going to add power, make it a meaningful increase in power (IE 6db more headroom). 2.2db more headroom is nice and all, but all the receivers you're looking at, are around 100w to 140w receivers. The difference between 100w, and 140w, is 1.5db You're better off getting a less potent receiver with better features, and supplementing it wiht an external Emotiva XPA3 amp or something like that. The difference between 75w and 200w, is 4.2db which is closer to a meaningful increase in headroom. Still nowhere near as meaningful as getting significantly more sensitive speakers though. All the above said, your N24s are flat out wimpy and will not benefit much from more power. Even if they're rated for 100w, they're probably already distorting by the time you're pouring 40 to 50 watts into them.
5) Go with multiple, large, subwoofers. One sub won't cut it if you want' the best bass in a real room. I recommend three. We can recommend you some kickass subs when you get to it.
So the number one goal for you right now, should be to run back and really re-assess what's going on with the room. Improve the ventilation, acoustics, bass trapping.