Biwiring just refers to connecting seperate cables (or conductors) to the treble and bass terminals of your speakers. However, you still only use 1 amplifier. Bi-amping thus refers to using seperate amplifiers for treble and bass. The theoretical advantage of bi-amping is clear, and there are definite improvements. However, for bi-wiring, its more controversial and I won't go into the theories at the moment.

Instead, I'm going to propound the stance taken by Roger Skoff of XLO, who makes my favourite XLO cables (could it be the funky colour scheme that I love? :)). His view is that biwiring brings minimal improvements and that you should rather buy the most expensive single wire cable possible instead of 2 runs for biwiring. XLO produces 2 grades of jumper cables using their type 5 and type 5.1 cables. Yes, the price of these jumpers approaches the price of a full set of AQ Indigo/Midnight :)

Huge gains can be wrought from removing that piece of metal, which is gold plated brass for all we know. (direct gold plated copper is very soft... and I don't think most speakers use that), and replacing it with a jumper cable using a top quality cable.

To see whether jumpers would benefit is easy. Plug your single-wire cable into the treble terminals and let the metal plate carry the signal to the bass. Then plug your single-wire cable into the bass and let the metal plate carry the signal to the treble. Listen to a audiophile quality recording with plenty of high frequency transients. The difference should be significant. If the difference is signficant, you can clearly benefit from using jumpers.

Hopefully, your dealer will sell you a short lenght of wire for these purposes. Look for a wire that isn't thick like a garden hose because in that short distance, you need a lot of flexibility. I think VanDenHul's the Wind is a good candidate. Myself, I used AQ type 4, which is long-grain copper (as a cheap $6.90/m experiment). I sliced open the blue jacket, and used 2 conductors for the negative terminals, and 2 conductors for the positive terminals. To provide shielding, I then covered the wires with the blue jacket which I sliced open earlier (OK, I can't tell the difference with or without jacket:)) You may wish to use spades to terminate the jumpers like XLO's jumpers, or just bare wire like I did, in which case, don't forget to spray on some Pro-Gold or contact enhancer to prevent oxidisation of the bare copper.

Plugging the single wire cable into the bass, with the AQ type 4 carrying signal to the treble, I could hear more top-end air and treble detail. A worthwhile improvement. Of course, there is definite room for improvment as plugging the cables into the treble direct, I could hear better treble and weaker midrange (my speakers are 2 way). Ultimately, I prefer plugging the cables direct into whatevers connected to the midrange as IMHO, thats the key part.

And hey, someone at soundstage is also advocating using jumpers with AQ type 4...

For a short time, I replaced by AQ type 4 with Van Den Hul CS-122s ($19.80/m), but now...

My biwiring results
Margil was offering (for the first time in my memory), all Nordost cables at 20% off. After struggling between splurging on Red Dawn or on some down to earth Blue Heavens, I settled on a 1.5m pair of Blue Heavens. The nice term about selling by the reel is that you can order it as short as possible as save money.

Removing the CS-122 jumpers, I plugged the Blue Heavens into the tweeter and the XLO 6as into the woofer, I noticed immediately a very significant increase in bass. Most of the increase came at a slightly higher region of bass; the 50-60Hz region I reckon. It seemed like the XLOs, being freed of tweeter duties, had more energy to dedicate to driving the bass. The midrange seemed a bit cleaner but I did not notice any increased detail. Of course, at this stage, with the Blue Heavens driving the tweeter, I had to make allowance for break-in, and they definitely sounded bright and splashy.

After some more break-in, I still found the Blue Heavens a bit too splashy in the treble. I then used the XLOs to drive the tweeters and the Blue Heavens to drive the woofer. Vast improvement I would say. The XLOs do not give away anything in detail to the Blue Heavens, and they sounded exceptionally detailed (definite improvement compared to XLOs alone, but I think 90%+ is due to the jumpers) driving the tweeters and gentle at the same time. The Blue Heavens on the bass, had what I could call a midrange to die for (at this price level). It sounded a bit rough as its still not fully broken in, but the midrange really shone through. No increase in detail compared to the XLOs but a bit more focus and coherence. Some might call it 'spotlighting', but I welcomed the increased focus as it helped with imaging, an aspect I'm not totally satisfied with (of course, thats because I want Proac Response sort of imaging :)). Bass was weaker than the XLO with jumpers alone, but I'm ok with the tradeoff (OK, so I nudged the gain on my subwoofer up a little bit to compensate).

Ultimately, I consider biwiring a worthwhile upgrade. However, if I were starting out, for the combined cost of the XLOs and Nordosts, I could get a speaker cable 1 grade up. That cable would definitely have more detail and refinement than a biwiring combo. Also, I wouldn't recommend turning the Blue Heavens into a biwire cable (i.e. 1/2 the conductors to bass and 1/2 the conductors to treble). The bass of the Blue Heavens is weak enough already and there is a correlation between the amount of 'cable' and the bass quality.

When I sit down and figure out the cost of the XLO 6a plus the Blue Heavens vs my S$1280 Zephyrs, I go : hmmmm.... But then, I still can't think of any speaker under S$2,000 that I like better than my Zephyrs.