[Andru08]

I'm still very much a newbie as to what I should get.
I'm hoping that someone can pointer me towards the right direction.
 
Below are the headphones I own.
 
Sennheiser HD650 <- This is my first pair of good headphones. I use this mostly to listen to music on my iMac.
Sennheiser PXC450 <- I absolutely hate the sound on this one. It sounds thin and flat.
AKG K702 <- this one is fantastic for watching TV. Wonderful bass especially when explosions happen.
Polk Audio UltraFocus 8000 <-- don't like this one much because it picks up noise from electrical equipment like my tv, computer or light, so I sits mostly unused. Also it doesn't function without power.
Audio Technica ATH-ANC7
Audio Technica ATH-ANC23
 
I use both the ATHs at the same time for maximum sound reduction when I travel on the bus.
 
I have my eye on the Sennheiser HD800 and the Audeze LCD-X and the HiFiMan HE-6.
 
I listen to classical, R&B, jazz and pop.
 
I also tend to use my headphones for all sorts of movies. I watch lots of dramas, SciFi, and action. 
 
I don't have a headphone amp yet as I also completely confused as to which amp I should get. Can't I just use my Yamaha RX-V 3800 surround receiver to drive my headphone or must I use a dedicated headphone amp?
 
If anyone can guide me towards one of these headphones or some other that would would work I'd be most grateful.
 
Which pocket headphone amp should I get to drive any of the headphones that I already own?
 
Thanks in advance.
 
Andrew