This is a well travelled repeating post theme over the last 15 years here on AGON
here is a very brief selected sample ....all with the same conclusions.
roll up your sleeves and do your research here on AGON and other audio forums.
(1) it is entirely system dependent.... and until you actually do an A-B bake-off... you won’t know.
(2) Some speaker manufacturers indeed do favour them (Vandersteen ....) but some of the top cable manufacturers (CHORD, NORDOST....) are opposed . Without prejudice to the effects that the absolute benefits are always system dependent, a large chunk of the high-end quality build brands are moving away from bi-wiring in favour of shotgunned runs and jumpers.
Biamping ... Different story.
E.g. NORDOST
http://www.nordost.com/downloads/NorseJ ... ctions.pdf
CHORD
http://www.chord.co.uk/help-and-informa ... ngle-wire/
".... Many hi-fi and home cinema loudspeakers have two pairs of binding posts. This allows the speaker to be either bi-wired using two sets of loudspeaker cable or bi-amped using two amplifiers.
As a general rule (and there will always be exceptions) we tend to find that bi-wiring will open out the sound stage and increase perceived levels of detail. However, single wiring will often sound the most musically coherent. There is also an issue with single and bi-wire speaker cables. In all the research we have carried out, a single wire speaker cable out-performs a bi-wire cable of equivalent cost. This makes a lot of sense; the single wire speaker cable has two high quality conductors and the bi-wire cable requires four. So for a given budget, we believe that a single wire cable will always out-perform the equivalent bi-wire cable, so much so that we no longer produce dedicated bi-wire cables..."
(3) Thus there is no silver bullet one size fits all answe ..... full stop.
https://forum.audiogon.com/discussions/2-runs-of-wires-or-1-run-w-jumpershttps://forum.audiogon.com/discussions/speaker-jumpers-same-brand-as-speaker-cables/post?highlight=B...
https://forum.audiogon.com/discussions/to-biwire-or-not-to-biwire-that-is-the-question?highlight=Biw...https://forum.audiogon.com/discussions/should-i-bi-wire-or-use-jumpers?highlight=I%2Bwire