Value of upgrading only 1 set of interconnects?

In my opinion the first cable upgrade should be the preamp to amp. Evert signal has to pass through those two components.  

I agree with eric.
There are two kinds of cables - Good Cables and Bad Cables. Usually the bad ones are the mega expensive ones. Kinda like fixn something till it’s broke. Whether it’s analog, digital or high speed data transfer, the criteria is the same: Low capacitance, low inductance and low resistance made using quality materials - high grade copper or silver with PTFE insulation, textile sleeve only if needed and shielding only if your situation requires and it usually doesn’t and good connectors. Everything else is a rue. If your system sounds to bright, sure you can tame it with a high dollar set of bad cables, but usually the problem is a miss-match of components or a need of room treatments; if your system sounds dull or muddy, it could be cables that don’t meet the criteria of good signal transfer or a week link in your system.....Jim

dorkwad, yes definitely, but usually I think double price. I always try to upgrade rarely but in as big steps as I can afford or think can afford. When new component including cable, burnt-in of course, is really much better you hear it immediately. There are more complicated situations when certain things are better and others are not or even worse, I had this fun comparing a few Purist Audio cables. And you know what - I sold them all and got the one that was better than them all in every respect !
Yeah, upgrading one set of cables might make sense but proceed with caution - you may throw the system off the balance and get worse sound. This is not straightforward matter.

inna,

I agree, you can set the system off balance or too far in one direction from neutral.  In my case, I loved what the Teo GC cables did in my system.  I used them from both of my front ends to the preamp.  BUT.. when I tried another Teo GC from the preamp to the amp, it was too much in one direction.  I have a couple good friends who let me borrow their cables or come over and we have a listening session comparing a couple cables.  We are agreed the extra Teo GC used at that pre to power was too much and substituting a lower cost JW Reference in that position made the sound better in all ways.  Better leading edge and somewhat better dynamics.  

Now, when we tried the double Teo GC (also called the shotgun or Schroeder method) vs. single, the results were even more impressive.  Other than higher cost, it was a no brainer.

Bob