Synergistic Research XOT Carbon Crossover Transducers

I use Carbon XOTs. They clean-up EMF at the binding post. They are easy to A/B and, like others have said, send them back if you don't hear a difference. Everybody's ears and systems are different.

I know have over 200 hours and for sure they have gotten.  soundstage is bigger as well as image depth and tone saturation .i bought these on Audiogon under tweaks 
Albert at Highend Audio gave me  free Priority mail shipping ,and make an offer 
maybe took few bucks off I paid around  $400. A true highend bargain  .

So if my speakers are Bi-Wire (four binding posts on each speaker), do I need two pairs of these?

Yes, if you bi-wire then in theory and according to the manufacturer you will need four pair which will set you back around $1K. Not cheap but there is a trial period. Heaven forbid they sound good for then what to do other than fork over the $1K.