Suggestions on Pre Amp/Amp or Integrated Amp

It sounds like surround sound is a requirement given your wife's primary use being movies and that music is not a big priority. 

There isn't much available for affordable high end preamp/surround processors.  By the time you buy a good 5 channel amp, it would be tough for $5k.

I think you'd be best off upgrading to a high end receiver.  There are a ton of options there.  Probably get a nice one for less than $5k. 

That probably isn't much help... 

The Anthem MRX 740 looks interesting.

https://www.crutchfield.com/p_973M7408K/Anthem-MRX-740-8K.html

I have that Anthem integrated.  Works and sounds great!

+1 Anthem is a solid choice for surround Sonics. A step above box store offerings. Better surround offerings would cost significantly more. 

"tighter, punchier bass, clean power, room correction and more watts"

A new receiver in the price range you list will definitely be a positive upgrade. If it was my choice to make, I would find a good used power amp, like a Bryston 3/4 or a Krell KAV 250 for your main speakers and use your current receiver as a preamp. No receiver will even come close to what an amp like that can do for your speakers. Also, taking the front speakers off the receiver should allow you to biamp your HTM. I had one and they like power. You won't get room correction, but I think you would be happier. Over the years, I've had several pairs of B&W's, and they really benefit from a good power amp. Either way, its just another option to consider.