Upgrade Speaker Cables or Interconnects

I would start at power conditioning first before anything else.
Once your power conditioning is in place move to power cords.
Power is the foundation for everything we build on.

IMO good clean power is like a component upgrade.
It's that important.

Good luck!

Barhi ohr, stereo 5!
Whenever I pass through a little town in Florida called Green Cove Springs,
I always stop in a little hole in the wall called Mush Armenian Kitchen.
Great lamb kababs and vozni for dessert! 

Race Car Driver:  I am having a problem with traction in the corners, what should I do?
Audiophile: Change the engine.

+1 stereo5 !!!

You could try upgrading through Ebay.
Some bargains to be had.
Easy to post, try out, and move on from if they aren't what you are looking for.

Managed to get speaker cables (RRP $1200 for $95) which I still use.

I'm currently looking at the same sort of thing. Mostly stock cables now so room for improvement everywhere. My approach has been to prioritize what gets the most use and is the weakest link. Speaker cables get used by everything so does the amp power cord. Interconnect between pre and power amp or most used source would be next. Digital cable to DAC probably gets used a lot too. If I decide to further upgrade one of those then I'll move it down the line to another less used component and put the shiny new one where it can do the most. Now I just need to wait until the jar is full of nickels and dimes so I can pay 25% of my systems value in new cabling.