Speaker Cables

While you are at it, I also recommend you change your crossover capacitors to the following:

https://www.partsconnexion.com/Jantzen-silver-cap.html

These are at a very nice sweet spot of price per performance ratio. There are many more better film caps but they are also much more expensive.

Changing the capacitors becomes a must, if you see any bipolar electrolytic capacitors (note that I said BIPOLAR) in your old crossovers. It is very unlikely that you will ever see unipolar electrolytics in a crossover but bipolars are possible. All electrolytics, unipolar or bipolar, are a ticking time bomb. Spendors are usually great quality but just check if they have any caps which may need replacing.

ProAc speakers have a reputation for being relatively even in response. If you'd like to maintain that honesty I would contact Audio Envy and have them build you a bi-connector set. I believe they're upgrading their SP9 orders to SP11's. The set that they sent me was phenomenal and more even in  response to the point that I no longer used my dirac correction and when I did an impedance sweep it was notably smoother.

Bear in mind that if you put a film capacitors in place of an electrolytic, you will generally be lowering its equivalent series resistance (ESR), and thus altering a fundamental characteristic of the crossover which affects frequency response.

Whether the deviation is sufficient to warrant concern will depend on the speaker in question. One solution is to place a resistor in series with the capacitor to make up the lost resistance. The more capacitors in the crossover, the more significant the issue.

Some people complain that after putting boutique caps in their speakers there are significant gains in transparency, but somehow they sound, ‘all wrong‘. or, ‘completely different‘. Now you have a fair idea why.

thanks again @cakyol @pesky_wabbit @decooney @twoleftears and others for your advice and good points

yes i did check - and the spendor crossovers used high quality box poly capacitors known to stay stable over the years - am glad to stay away from cap replacement given their tricky measured vs listed values, esr’s etc etc - spendor evidently went to great mains to match and select caps way back to their manufacture of the bc1 and successors

tinned ends or solder cups points noted 👍👍

I have been auditioning Kimber Kable’s Bifocals and they sound great - still questioning the dollar value but clearly sound better than other speaker cables in my system. 
Mixed feelings because I was happy using cheaper cables.