Remarkably better sound possible with just 1 system component change?

I could have posted this discussion to a few other categories but chose this one because discussions related to 2 of the 4 components in question belong here.

So it's been ~2.5 yrs since I purchased my current system. I did a lot of research at the time here on audiogon, but no auditioning, and put together a system that sounds very, very good to me.

While I have no complaints, the itch to upgrade has surfaced recently.

I am curious as to whether you guys think it will be possible for me to replace just 1 of my primary 4 components and obtain significantly better sound as a result. The more discernible and obvious the sound improvement, the better obviously. I am not looking for a marginal upgrade - I want dramatically better sound. And I am not looking to replace more than 1 component at this time. I am hoping to get a few ideas/candidates and then may decide to audition some of the recommendations before making a decision. Hopefully some of the upgrade paths are such no-brainers that I may even be able to take a leap of faith without auditioning. Note also that acoustic room treatments are not viable in my current listening location.
My current 4 part system:

1. Lumin D2 - 100% of my listening is streaming via Tidal
2. Mcintosh C2600 preamp
3. Mcintosh MC452 amp
4. Focal Kanta 2 speakers

Cables are Cardas Golden presence RCAs from the Lumin to C2600, Cardas Clear Cygnus XLRs from the C2600 to the MC452, and Kimber 8TC speaker cables to the Kantas.

Soundstaging, dynamics, imaging and overall clarity are all great. I have to say I love the Be tweeters. And the bass is punchy, tight, fast and certainly sufficient for my needs. Vocals and overall sound are warm, liquid smooth and analog-like, just the way I like it. (Forgive me if I've botched some of the characterizations - I'm no expert at this). The only thing I can think of that could use some improvement is the sound quality at lower volume levels, although that is not terribly important to me since most of my listening is in the 90+ Db range. Would be nice, though.

So while I do love the overall sound, surely dramatically better sound can be obtained via a 1 component swap? Budget is ~10k. Or will I need to spend more, or upgrade more than 1 component to achieve the desired result?

Thanks in advance for your time and thoughts.

Without a doubt powered subwoofers, ideally with room correction. I use a JL Audio F110. You could probably use two of those, or even two F112s in your room and hear a huge improvement. Also room treatments. 
For those suggesting wire, interconnect, power cords or AC tweaks -- given his room (he gave us a picture) -- do you think this would result in a 'remarkable' improvement, which is what he's after? Given the room's situation, I cannot see how these would even hold a candle to suggestions involving room acoustics.
I have a very difficult room since it is over the garage. I have Focal Kanta 3 floor standing speakers and added a Simaudio 680D streamer dac to my system and it made a huge difference in sound clarity and overall sonics. I am using a Anthem Str-Integrated Amp with Arc room correction. I have listened to a lot of the same music on CD as well as Streaming on Tidal Quboz as well as using Roon and found that certain songs are better depending on witch source I use. If you only stream a better Dac and Streamer might help.
Your cabling should all be the same technology for the best performance. You did not mention your power system. Power is the foundation. Depending where you are you may want to consider a power conditioner, but get your self some good power cables. I suspect you will probably forget about the component upgrade. I could be wrong I was wrong once before.
@chandybe Ok then let’s go with your balls to the wall lifestyle!  The speakers you have do not fit that sort of environment.  It seems to me you would really enjoy speakers that deliver a more dynamic, punchy room energizing sound.  I would go JBL 4329 (or higher), possibly Klipsch Heritage series.  The sense of liveliness and energy would really rock that room and be fun to listen to during a party as well.  That kind of change will invigorate your listening experience and add excitement to your music!