Best components to optimize Martin Logan 50XT and Edge in walls


Good Day All,
  I am by no means an audiophile and am looking for advice to optimize my final system.  Currently looking a 5.1. Home theater is the main usage for system located in the living room.  House hold compromise has led to equipment listed in title.  My current concern how to get the most out of my system within cost constraints when competed.  I would appreciate your recommendations for an amp, sub woofer, and in wall rear/surrounds (1 set of speakers) that would accomplish this . Pre amp/receiver will change over time, I assume.  Listening area is 18 by 20 with 20 foot vaulted ceiling, tile floor, open to kitchen on one side(not included in dimensions), double doors open on the other, and 2 windows.  Room acoustics will be another house hold issue.  Am recently retired and hope to spend around 5k or less now to accomplish this with possible upgrade path.  Any help from experts appreciated.  Judging by the quality of systems I see discussed here if I have belittled this site in any way I apologize in advance.  
lovepoozer
Sorry, no recommendation for amp or sub, but it is a "no brainier" that you should use a Martin Logan in walls for the rear surround.
  OK, I understand more now, thank you. For HT, the classic answer is that the speaker drivers should match, at least in the three front speakers. I have five NHT speakers from 2000, with drivers that match in the front three speakers and two in-wall surrounds. I use a Velodyne DD-12 subwoofer. I use a McIntosh preamp-processor and 5 channel amplifer. Humbly I say my system sounds really good.  But my room is smaller than your room, and is maybe only half the size, more or less, and does not have a high ceiling. Maybe one of our members has a room about your size with a high ceiling and could offer you better specifics as to an amplifier/subwoofer.  
@lovepoozer - Can you tell us exactly what components you currently have?  It's not exactly clear if you already have a HT preamp/processor, or if you just have a few speakers.
Thx all for input,
I'm currently using a Denon 910w and a old Jamo A3Sub.5, which clearly sound dull and lifeless.  This is why I need advice.  The clarity, even with this amp is good but I know it can be so much better.
If that Denon is the AVR-910W, then replace it first. Those speakers need much better power. Even though it's rated at 95w/ch, that's with only 2 channels. With 5 channels, it's likely about 60w/ch, and with very little current. Also, it has no preouts to add a power amp. Those speakers need so much more than a $500 receiver. Forget about the subwoofer until you get adequate power on the speakers.