Bi-wiring with different cables for HF and LF?

"Ozzy
I am using a pure soft annealed 99999 silver wire as speaker wires.
I have 14 gauge on the low end and a 18 gauge on the high end."

Where would one find such wire, and what's the cost? That sounds like it might be nice for the low frequency run.

I bought mine on ebay a few years back before the price went through the roof. I'm sure you can still find it just might cost you more than you think.
To make a 12 foot biwire pair you will need about 50 feet of 14 gauge and 50 feet of 18 gauge.

I cleaned the wire and placed it into oversized teflon and then lightly twisted the positive and negative wires.
At the speaker end I also found that a rod type magnets on each side of the cable (attracting through the cable) also a plus.

If you are going to experiment using silver cables for your bass run, I'll offer a suggestion. Since silver is expensive, and you don't have your mind made up as to what will work best (I make that assumption based the fact you are experimenting), I would to borrow some silver cables if you can. Generally speaking, what people like or dislike about silver cables, tends to be in the high frequencies. For low frequencies, its very possible that using silver offers no advantage over copper.

If you try copper, as well, you may want to compare solid core vs stranded. Again, generally speaking, stranded seems to offer better bass performance over solid. Thats not the only factor, but something to keep in mind.

I don't agree that stranded copper provides better bass than solid wire.

Silver cable sound quality can be all over the map.
Use the highest grade soft anealed silver wire and it will beat most any high $$$ cables. I personally have owned or have tried in my system many of the top of the line speaker cables and I have no desire to switch from my DIY Silver 99999 soft anealed speaker cables.

Stringreen

Coherence is compromised

After more thought, Vandersteens comments, checking the Legacy site, I have to agree with Stringreen. Your speakers are voiced with well thought out crossovers to achieve max coherence. By mixing cable you could potentially effect speed, transparency, musicality and most certainly change ideal coherence through the frequencies. Will it damage anything? NO. Could it sound ok? Yes. Is it the ideal arrangement? Not close. Getting better sound is more a function of removing offensive artifacts than adding superflous components. Thank you Stringren for pointing out the path.