Confused: Should I Upgrade Cables or Amp first?


I currently have very long runs of Audio Art SC-5 speaker cable (about 20 feet) that, due to WAF issues, are routed through holes in the floor, under the house. I use MIT AVT speaker interfaces, in an attempt to compensate for resistance.

Speakers: Silverline 17.5 monitors. Components: modded Jolida JD100 tube cdp and modded Jolida JD302 tube (EL34) integrated. 

I can afford to put $2500 into the system at this point. I could re-route cables through a wall and relocate components into another room, thereby dramatically shortening cable runs to 10-12 feet and enabling bi-wiring. I could also afford to upgrade all cables. OR, I could leave cables alone and upgrade amp.

Which is likely to produce biggest improvement? 
stuartk
stuartk-

you have a nice, simple system. I would keep the Jadis gear together.
I love cables/cords, and am a "cable" guy first.

Whichever way you go, audition/demo any gear and/or cabling prior to any purchase. Keep me posted and Happy Listening!
stereo5: thank you for your valuable input! I'm expecting delivery of a Parasound Halo Integrated soon from Audio Advisor, so I will focus on amps. 
@jafant , Jadis? Where do you see Jadis? He has Jolida, not Jadis.

I would ask first, what do you feel you are missing?
If you are happy with the sound, then just enjoy the music and spend the money on software, a vacation, or maybe a turntable.
TY- jmc.
Jolida -corrected.

I would like to read more about the modded integrated amp.
In looking at the system as is, I don't see any glaring weak points.  The Parasound has 150 wpc, and to my ear is on the warm side, at least the A21 and P7 combo I have is.  The speaker cable is 14 gauge, so I suppose could be improved upon by shortening the 20 foot run.  

Either way, please report back on your impressions of the Parasound Integrated.  I'm guessing the Jolida has about 50 wpc?