Optimize Stereo Experience - NYC Studio

Hey, happy new year to all - new to this board but been lurking for a couple of years now.

Needed some help with this 2.1 stereo system I've assembled in my small NYC studio apartment: NAD T 758 + pair of KEF R900. I use Amazon HD and Spotify to stream the music. Below pic shows that my room layout doesn't allow for placing the two speakers in a straight line (have tried all other room configurations, unfortunately this cannot change). I have so far 'corrected' this via DIRAC and sounds significantly better with it. Had the following few questions in case anyone case help.

- Any further additions to the system hardware to make the sound improve significantly (amps, wires, speakers etc)

- Would a center channel speaker make sense. I mostly listen to music but sometimes do watch TV/Music too. I have a feeling the dialogue can be improved if I add a center channel.

- While I tried to test A/B Spotify vs Amazon HD and couldn't hear a very drastic difference, would love to have people's opinion here. I would definitely prefer Amazon HD over Spotify, but the crappy UI of the Amazon in BlueOs (NAD) makes life much easier when browsing for new music on Spotify.

- While I can't change where I live, any other tips / suggestions re speaker placement?

Greetings fellow NYCer! I have spent most of the past 15 years trying the best I can to optimize my listening situations in various small apartments, so I know what you’re going through. I actually installed a murphy bed in the 2nd bedroom of my current apartment just so I could have it double as a listening room. The things we do for audio!

I know you ruled out changing the configuration of your space, but looking at your picture the first thought I had was: why not mount the TV on the wall, get a narrower media console, and consolidate the two speakers together in that space to the left? They would be a bit close together, but if you set up some seating there, you could have a nice little nearfield situation.

I’m not sure exactly what you like or don’t like about the sound you have now, but moving forward you could consider getting an outboard DAC, and maybe think about separate preamp and power amp components. Tubes, if you fancy the sound signature they offer and want to have some fun - in a space like that, you probably aren’t listening super loud, and at 90db the KEFs are fairly sensitive - so you can probably have a lot of fun with a modestly powered tube amp.

Again, not sure what your preferences are vis-a-vis hifi 2 channel listening versus home theater, so I’m just spitballing here.

Good luck with it!

You can't bring the left speaker forward, and move the right one to the left? Townshend Podiums are no bigger than whatever is under them now. Any sort of springs will both improve imaging and reduce sound going into the floor and bothering neighbors. But nothing really will give you stereo other than moving to where everything is somehow equidistant and symmetrical. Not with the room just with you and the speakers. That one requirement is what we call non-negotiable.

Your problem is not being equidistant its always going to sound like 2 speakers instead of a sound stage. Adding a center channel will only prove the fallacy of HT, because you will still not be equidistant so no sound field only now it will be coming from three instead of just two. And the HT processor needed to do this will only ruin stereo. HT is what we call a lose-lose proposition.

+1 on the DAC — great gear is available for $500 to $2000, and the electronics have made huge improvements in recent years. New or used (as long as it’s 2015 forward) it’s hard to imagine you’ll find better bang for the buck. 
I second zm's suggestion (smaller console, right speaker brought closer to the left) and it may be acceptable even without focus on nearfield. It will still have some shortcomings (wall next to the right speaker). Otherwise, room treatments may be your best bet. If nothing else, more carpeted surface. Your neighbors will thank you, too (somewhere in the contract, it likely says that you have to cover 75% of the floor surface anyway).
There was an interesting post hear a couple of days ago about corner speaker placement. I believe that speaker placement is a huge part of the battle. What will work best in your room can only be discovered with  experimentation.