Very short speaker cable length recommended?

There is a small on-line cable company that makes wonderful cables, some of the best I've ever heard. When my new wall unit required that I move the speakers about 15' away from the source I decided to go with long interconnect runs of this cable into mono-amps and short (6') runs of speaker cable. The bass dropped off dramatically, as did the impression of power and dynamics. When I changed interconnects to those containing thicker, heavier wire things returned to normal.

It seems to me that there are definable, quantifiable values that determine whether this or that cable is electrically suitable and will perform as expected in any given situation. Certainly there are differences between the sonic character of this cable and that by virtue of their design and the materials from which they are made, but we as consumers should not have to play guessing games with electrical parameters and it is high time that manufacturers step up to the plate and start supporting our efforts at component matching by either standardizing or disclosing specifics that directly relate to component/cable matching.

Go 6.5 ft or longer(2.0m)speaker, its the more optimal range overall in most cases it seems, unless maybe running a non-full range speaker, like a woofer section or something running under 250 hz lets say then maybe 3ft or less would be more effective... Even with interconnects it seems Half meter might be worse sounding than 1 meter standard in some scenarios as well, I have no real world explanation for it but there it is.

Even with interconnects it seems Half meter might be worse sounding than 1 meter standard in some scenarios as well

It has to do with the electrical properties of the cable at the specific length as it couples with/influences (i.e. enters the circuit) the stability and the impedance of the source loading (output stage) and the impedance and type of input of the load.
See Sean's recent post in "diy interconnects review".

>>Go 6.5 ft or longer(2.0m)speaker, its the more optimal range overall in most cases it seems<<

There is no empirical data to support this and any knowledgable cable designer/manufacturer will always recommend shorter paths when possible.

Actually from my understanding if you go too Short then the tweeter and midrange can become more forward or even brighter in many cases(and I have experienced this), as the longer lengths keep the speed down a little bit helping for whatever reason the impeadance or what have you a better stable point to work in or something.. Now I have actually seen manufactures go to the extent to actually LEngthen considerable longer than needed Tweeter leads and things inside the cabinet even in order to somewhat time Align the drivers to not be to forward to the Bass drive... Sure Bass will probably never suffer from super short Current capable cables, but I could see how a speaker can be a bit un-balanced if you have super thick same shot length feeding the upper part of the crossover, maybe it will have Zero effect, try it, thats the name of the game.