Assymetric speaker cable lengths?

Ah, that issue again! Here is something else to worry about.

The earth is rotating...moving East at about 700 mph at 45 deg lattitude. So, the speaker at the East side of your setup is moving away from signal while the one to the West is moving towards the signal. Thus the transit times of the signal will be different even if the wires are the same length. Furthermore the Dopler effect will cause frequency differences. The obsessive audiophile will therefore set up his speakers North and South.
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As Shadorne pointed out, impedance is the big issue here. Check out Townshend Audio's website; their Isolda Matched Impedance cable is supposed to tackle the issue (have never tried this myself though)
http://www.townshendaudio.net/index.php?option=com_content&task=view&id=32&Itemid=86

The tube load theory doesn't hold water @ your lengths. Low impedence spkrs. w/ a bumpy impedence curve (>90% of the spkrs. on the mkt have less than ideal impedence curves) can be overcome by going w/ a heavier Ga. spkr. cable.

ok, im going asymmetric. thanks