advantage or disadvantage going biwire vs single

Probably not...but if you want to try biwire, experiment with cheap wire. If you don't think there is a difference you will have wasted few dollars.

I biwired my MG1.6 using small, AWG24, (cheap) wire for the tweeters so as to eliminate need for a tweeter padding resistor in the crossover. The sonic change, if any, was slight, but I do see some benefit (probably completely theoretical), and, being lazy, I have not taken the trouble to change back.

I bi-wired my Tannoy's for a while with decent Synergistic Research speaker wire. I've since gone to single wire (Dimarzio) and a quality (Onix) jumper. I like the sound better. It might be the cables. There is the train of thought that the two sets of connectors are really only for bi-amping. Because of the internal X-overs, separate wires don't add anything, only separate amplification. I cannot afford to bi-amp and the differences i heard bi-wiring were subtle, at best. There aer those who will swear by bi-wiring and I've no argument with them. Bi-wiring is a trial/error thing for each set of speakers and cables. Some speaker manufacturers even encourage bi-wiring. I don't believe there is a right or wrong in this situation. Have fun.

It usually depends on the speaker design.

Some speakers come with high pass and low pass filters (crossovers). With this design, biwiring usually makes a huge difference.

I envy you guys that can use just one cable. I tried mine with one cable compared to what I now use and the difference was night and day. My speakers prefer QUAD wiring.

The key here is to experiment, and ask others with the same speaker. Now, with audiogon, you will probably get a lot of feedback.

Good luck,
Richard

what kind o speakers ?

Since bi-wiring is essentially just a very long jumper (back to the amp connectors), I can only theorize that true improvements are made through wire matching to the frequency and current requirements of the component speaker loads (since both sets of wire start at the same place on the amp).

I propose that a wire composition, wind and guage matched to the portion of the speaker load would be required as compared to simple duplication of the wire from the amp to the x-over. Maybe a large guage, few strand, copper based wire for the low end, high current and a multi-strand, silver, smaller guage wire for the high frequency, lower current high end? (sort of an inductance matching effect?)

Your thoughts and/or test results are appreciated.

P.S. I just bought a pair of Maggie 3.6Rs and am considering bi-wiring, but find it hard to understand the "normal" bi-wire solutions vice simple good jumpers.

From my limited knowledge and perceptions, here are some advantages of biwiring.
1. The larger magnetic fields created by the bass signals don't modulate that of the high-frequency circuit.
2. Especially with a 3-way system (or at least one with a low--below, say, 1KHz--crossover), one can use lots of less-expensive conductors to optimize damping factor (= definition and control) of the bass system.
3. With either crossover, one can still spend less money for the optimum combinations of conductors to achieve the quality one wants. For instance, one can use quite-expensive-but-smaller-gage super-high-quality conductors (such as AudioQuest's KE-4, a 2-pairs, all-silver cable) for the tweeters while using a larger-gage, less-expensive cable (such as AQ's CV-6) on the bass/midrange.

Most of the advantages of biwiring can be achieved by single-biwiring, ie using the various conductors of a single cable for the 2 parts of the speaker.

I just bought a trio of premium AQ cable for my fronts. For the Aerial CC3B centerchannel 3-way speaker, I used inexpensive-but-high-gage Type 6 on the woofer and KE-6 (3 pairs of silver plus the DBS system) on the midrange/treble. For my 2-way (high-crossover) Kindel PLS-As, I used KE-4 (2 pairs of silver) on the trebel and KE-6 on the bass/midrange.

My system has never sounded better, with sweet, clean, detailed treble and midrange and great bass energy and control. BTW, I was using quite-good AQ cable previously. LOVE those silver conductors!

I found and lost an article which described the pros and cons and theory behind biwiring which prompted me to un biwire my new tyler custom linwoods for a test.

The result is that the sound isn't as tight, but its much fuller, richer, better imaging and better bass. For these speakers, with a longer wire run, biwiring was a mistake.

Of course in my den, I have some tyler reference monitors which I think sound better biwired.

http://www.sonicdesign.se/biwire.html

A bit late chiming in here, but I just defeated the bi-wire provision on my speakers, and to me the sound is noticeably smoother, fuller, and more coherent. I've only listened to three record sides since doing it, so it could just be the psychoacoustic effect by which "changed" is oft initially perceived as "improved". We'll see.

I realize that my brief description of the 'new' sound also could be read as evidence of rolled off treble, but I don't think that's the case here. My system at times shows some glare or brightness, but I think this is more in the mid to upper midrange than the treble, which could put it somewhere in the crossover range of my speakers (somewhere around 2.5-3 kHz). It seems reasonable that defeating the speakers' bi-wire capability could affect this frequency region.