Long ICs versus long speaker cables

I read a lot about specs on this forum and everytime I assemble a system based on specs I walk away disappointed.

My best sounding systems used either short speaker cable and short interconnects or short speaker cable and long interconnects.

Amplifier manufacturers I have spoke with recommend short speaker wire since it transfers the power to the speakers.

I am faced with the same question in my case and need advice for the following setup:

CD: Nagra CDP
Pre amp: Nagra PLL
Amps: Nagra VPAs
Speakers: Verity Parsifal Ovation

Currently my units are all stacked near each other, leaving a 4m long speaker cable run from the VPAs to the speaker. I am about to order a Purist Proteus Provectus 4m speaker cable but didn't want to make a mistake... Would such a length have a noticeable sound degradation?

Having the amps close to my speakers is highly impractical for me but not impossible. Is it better to get 4m long RCA interconnect cables (XLR is not the best solution for my power amps) in my case and a short speaker cable(considering the specs of the Nagra pre-amp)?

In order for me to go for a long interconnect solution, the sound must be clearly better otherwise the logistics issue that will exist will not be worth the hassle. In any case, I thought that going for a such a high quality speaker cable will minimize or eliminate the negative effect of the long speaker cable run as opposed to the long RCA interconnect...

Opinions appreciated!

Well I can't imagine the price tag on the Purist cable, but maybe you should do yourself a favor and see if you can try some OCOS cable. These are only made for speaker connections and are well known to be suitable for use in long lengths. I use a 5.5m pair in my system. No degradation of sound versus shorter speaker cables I own (including a $2000 pair). If you want, you can double up on the OCOS and use two runs per speaker (not bi-wire, same binding post). This is supposed to yield even better sound. You don't hear much about this brand but it is made by Dynaudio.

Logically I would probably go with what is more cost effective and an eye on the future or heed Elizabeth's suggestion. If you ever change rooms or configurations, it might be hard to get rid of a 6 meter interconnect. Also, at this length, I personally would want to use a balanced interconnect. If my gear did not accept balanced interconnects, I would probably just go with the longer speaker cables.