Which interconnect cable to upgrade first

looking for better soundstage and a tiny bit warmer sound without top end harshness.

If you really want significant improvements in these areas, try this AZ Silver Ref ll.  It’s half price here, so if it doesn’t work out you can sell for little/no loss, but I’ve used these for years and think you’ll be thrilled with the results. 

https://www.usaudiomart.com/details/649798116-acoustic-zen-silver-reference-rca-one-meter/

thanks @soix I’ll take a look.  

@ghdprentice here’s my setup:

Lumin T2 -> Parasound JC2 -> Parasound JC5 

I upgrade closest to the source.

Going against the grain here but I find better cables from preamp to amp the critical link therefore deserving your best IC's there!

Nice on the JC2 can't wait to get mine to mate with my JC5

Experiences will vary depending upon each person's system. I wish there was one answer that works for all but there isn't.