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?

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. 
If within your budget, CS2 and LS footers from critical mass systems will change your life.

Also agree with the equidistant rule.
A NYC studio...well, at least it's bigger than a walk-in closet....;)

Decouple from the floor, yes.  Older spaces (wood framing) infamous, newer with a concrete/steel framing and thin walls a close 2nd.
Yours appears newer...

'Closer together' ain't going to yield much, the Dirac is going to 'steer left' to compensate imho.  An apparently 'open-ish' space on left vs. 'tight corner' on right almost demands a version of acoustic treats.  1st go suggestion would be small and portable...what's the difference btwn L & R separately with pink noise (and perhaps a tone sweep)?

MOR architecture is the bane of audio....I've dealt with those devils, best always comes down to the best 'average that works, +/-...'

But have fun in the chase, always a great reason to play with the stack. ;)
BTW....@ kmalhotra....welcome to the show that never ends...;)

I appreciate your approach to the minimalist system with the PC....*s*