What to add or change for my system?


This is my first post, so please have pity on me if I break any rules.... :)

I immersed myself in this hobby a few years ago, and I'm completely hooked.  And best of all, my wife is.....almost hooked.  I initially purchased speakers from Axiom, OPPO 103D from OPPO, and Parasound preamp and amp from a local dealer.  These were connected with Kimber Timbre cables.  I also have a Furman Elite power conditioner.

All of that changed in December.  My system now consists of:
  • Martin Logan Summit X speakers; purcahsed new on AG
  • Plinius Hautonga integrated amp; purcahsed on AG
  • Oppo 105 that has been modded by Tweak Audio for even better audio; purchased on AG
  • Bryston BDP-1; purcahsed on AG
  • Gustard X20 DAC that has been modded by Tweak Audio; purcahsed on AG
  • Gustard U12 USB interface; purchsed new on Amazon
  • Clear Day silver speaker cables; direct from Paul, a wonderful person!
  • Avanti Audio interconnects; direct from Avanti
  • Furman Elite power conditioner; Audioadvisor

As luck would have it, I just got a nice bonus and feel the itch to add to, or make better my system.  Not knowing what to consider, I'm hopeful to get some suggestions from you.  If this was your system, and you had $3-4 thousand to spend, what you add or replace?

Thanks for your thoughts!!!
smills59
Looks like you made a huge leap the first time you upgraded . Looks to me the changing of amps/integrated would reap the most significant sound change . What are you looking to improve upon or change ?
As Randy stated room treatments Can be a big sound change too
Do you have your speakers plugged into the Furman ? The stats i've owned have responded well with plugging them into a conditioner or Furutech  receptacles
I was in Japan a few months back and went to Akihabra for a day.  It's a section of Tokyo that is packed with audio stores.  It's amazing!  While there I did purcahse two receptacles, but I don't remember the make.  The power conditioner and the speakers are plugged into these.  

I was thinking the integrated might be a change, but it does sound nice.  The Plinius puts 280 watts into 4 ohms.  Just not sure what additional power will get me (noob).  I listen mostly to jazz and some 70's rock.  Also don't listen at very high volume.

Would the room treatments go behind the speakers? 
Power numbers are not what you should strive for . No telling what you will get by going with more power . Just know you will get a change in sound by changing the Plinius is all .
What is it you think could be improved upon is the question you need to answer .At some point you will feed the Martil Logans with gear that cannot be improved upon . You may be there right now for all we know .
If it sounds good, why tempt fate? 
If not, then tell us what you are lacking or think you are lacking?
Bob