I am in the market for a new pair of cables.  Last year, after a lot of online research, I decided to try the Clear Day Double Shotguns only to find out that they are not longer being made!
I am now considering, after reading a number of rave reviews, getting a pair of Dueland 12ga cables.  The only thing that is putting me off is a few online comments saying they are not good with low efficiency speakers.  I have Spendor s3/5R which are 84db.  I have a asymmetrical setup so they would be 5' x 13' in length.
Anyone with experience regarding this?
I've had some relatively expensive speaker cables over the years, but now use 12 gage Dueland from Acoustic BBQ in both of my systems.   They take about 100/ 150 hours to break in, but are quite good once they settle in.  See ads from Audiogoner Grannyring.
 Looks like you are using yours with Harbeths which have the same 84db efficiency rating as my Spendors so it seems that the Dueland should be fine.I will check out the Acoustic BBQ offerings as well.
I agree the Dueland 12 gauge should work fine and sound very good after break-in. Very hard to beat for the price!
1+ pdreher
It´s Duelund, no Dueland.
Are you saying one cable will be 5 feet long and the other 13 feet?  I don't have the science behind this, but I'd think it'd have to introduce differences in resistance and other things as well.  I wouldn't do this if this is what you're thinking, but maybe some smarter people like @almarg or someone can educate us more on this. 

Jesus, you are right! " It' s (It's)  Duelund no(t) Dueland." 

Soix:  As with all things cable related there doesn't seem to be anything like  complete agreement on whether using two lengths of cable is detrimental to the sound.  I really want to avoid having a big coil of speaker cable behind my rack which also might not be desirable soundwise.  I am using Kimber 8tc now with different lengths and don't hear any bad effects but, of course, I didn't compare them with anything.I would be interested in hearing Almarg's opinion which is always well informed.
No problem with different lenghts. Zero issues.  I have a 10 and 20 foot lenght and my sound is glorious! Plenty of folks have differing   lengths and the sound is exactly the same as equal lengths. I have made many unequal sets for folks. 
Grannyring:  Thanks for your advice.  I no longer feel any hesitation in purchasing them.
I'm sorry.  I'm an idiot.  And I learned something.  Might be tough to resell them though.  Just another thought. 
Soix:  Don't be sorry!  A lot of people feel that all cords must be the same lengths or the wrath of the great audio spirit will descend upon them.  In some cases they may be right.
They would be harder to resell but the price is pretty low so it is a risk I am willing to take. A number of experienced audiophiles swear by them so I feel comfortable giving them a try.
Are you still looking for the Clear Day Double Shotguns? I have 2 that I’m planning to put for sale.  One is unused and the other has been used a little bit. Let’s talk