Odd length speaker cables

A few years ago I murdered a perfectly good extension cord looking for a good speaker cable. Needed 6 feet on one end and 12 feet on other. Tried other lengths (2 ft-15ft, 6ft-20ft etc) and found that any mis-match of length more than 20% was sonicaly notable. Have tried more recently "better" cables with similar results. Shorter-longer not better-worse, just different. Moving speakers around will change perception due to different sonic presentation of different cable lengths. Regards to all that have commented on this aggravating topic. Mike

Thanks everyone. I spoke to a local dealer who " does not believe in significant difference". He claims that years ago he conducted double blind studies with groups of audio enthusiasts, repeated each test 10 times and less than 20% were able to tell a difference 20% of the time. He moved to a smaller space fiew years back and has a 50 and 30 foot run of silver sonic that he cant use and will part with for a $100. I will pick it up and experiment myself.

Your dealer is wrong.
The better the equipment the more you will notice the difference in the uneven cable length.

Really, IMHO you should go as short as possible.
I think you should rethink your equipment layout and try to make the runs close to the same.

Your dealer is wrong.
The better the equipment the more you will notice the
difference in the uneven cable length.

Well, that assertion should settle it for once and all. All
you have to do is be able to accept it.

I can't.

I don't believe 99.9% of people could tell the difference. Granted, its not optimal, (on paper) but, can YOU hear it? In a blind test, I would put my money on no every time.