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
marktomaras--
Wow... a lot to digest. Very kind of you to take the time to lay it all out.
I will have two amps to try, first, and it will no doubt become apparent soon enough whether they'll make much of a difference. BTW, I'm not at all opposed to trying a stand-alone DAC but I do find the reviews very intimidating, as I know so little about the technology and understand none of the terminology. The Parasound Halo has an internal DAC but  I have no idea how advanced it is or even if it can be bypassed in favor of an additional stand-alone unit in future. More research/education is required.
As for speakers, a "merry go round" friend had the Acoustic Zen Adagios for awhile, which I liked. Maybe the Adagio Juniors would be a possibility for me or a Zu. Subs-- I'm not familiar with the Wisdom SCS-- I will check it out. The above are options I feel most comfortable with exploring first. Thanks again for your kind assistance! 

stuartk:

Lots of ways to spend money and improve systems but first  priority is to have everyone happy in the house. If you have not done so, I suggest upgrading the wall outlets and fuses to your music source and amplifier.

The Synergistic Research Black fuses and their  wall outlets come with a 30 day trial. It is a fun audio experiment to do, and for many the price performance gain is very good.

David Pritchard

David; my wall outlet is upgraded, although it was done many years ago and so I do not recall what brand/type was installed. I will check out Synergistic. Thanks.  
stuartk, have you tried experimenting with the streaming services yet?

You can get a Bluesound Node 2 from Best Buy and you get 2 weeks of no questions asked returns for a full refund.  I recommend buying one to try it out for free, and you will likely want to keep it.

If you haven't tried this yet, hook up a node 2, get the trial of Tidal HiFi for $15 per month, hook up the node to your amp, and control the node with your smartphone.  

Super super cool.  If you like it, when you eventually rip your CDs, you put them on a network hard drive, and they stream to the node.  It has a built in DAC as I mentioned, but you can also use a higher end DAC.  I have a similar setup, but I am using a mac mini computer, external hard drive connected to my DAC. 
marktomaras;
You are evidently much more comfortable with these newer technologies than I am. I have no idea what a "node" is!