Will power cable work well as speaker cable?

I've not tried it, but I've read many anecdotes that proclaim Romex to be an amazing speaker cable. But a bear to get into place. If you do use your 10/5 Romex, (you sure about that? 5 conductors plus a ground? I've never heard of that..) don't use the whole thing, just strip the conductors out that you need. 2 for regular cables, 4 for biwire. You might even want to try a helix configuration, based on williewonka's post above..

@toddverrone   Yep,  I was going to use a twist of 2 for positive and 2 for negative.... I've got about 30 feet of it or if you look at it another way,  I have 5 -  30 ft runs of solid core 10 guage.  I've had it for a couple of years... I still don't have one of those little round tuits.  

Hahaha! I had to read that last part three times..

Man, 2 x 10awg per polarity is a bit crazy. I mean, unless you’re pushing 2000 watts..

I’ve been making lots of cables and was loving some braided cat 5 cables. However, I recently made a pair of cables like williewonka’s link above, the helix. They sound great. They key parts of the great sound are the coil architecture and the double neutral. Check it out. It could sound amazing with Romex, but your hands will be sore, making the coils!
Whatever you do, those are going to be some stiff cables!
How the crunk are you going to fit all that wire into a binding post?!

@todverrone & @timlub - Actually - if you stick to the formula of 2 neutral and 1 signal...
- The neutral, being coiled, is quite flexible and it’s weight helps with flexing the signal conductor - so cables made with Romex are actually quite flexible.

I started with a Romex helix when I developed the power cable. It worked very well, but I was concerned with the live conductor breaking because of fatigue due to a lot of flexing, so I decided not to promote it.

Other things with Romex that I found (especially for power cables)
- Crimped terminations fail very quickly so you have to solder all connectors (e.g. spades, bananas etc...)
- not using spades (for power cables) results in less than optimal power transfer

Other than that - It should work very well for speaker cables, but again, I do not promote Romex use for the signal conductor because of the fatigue issue. I prefer a stranded signal conductor just for that reason.

But give it a whirl - it’s easy to change to a different signal conductor once you hear the abilities of the Helix geometry.

I think you will be pleased with the outcome.

Cheers - Steve

Update:
I replaced the power cable with 12ga oyaide speaker wire. Now using the power cable as it was designed to be used. Although it worked well as speaker cable I couldn't get past the fact that it wasn't designed for it. That and in my experience I get more bang for the buck (sound improvement wise) with power cables in my system than speaker cables. The beauty of this upgrade is that I now have Oyaide Tunami power cables going to all the electronics (except the TT motor) associated with the analog portion of my system. I will be replacing the IC's with Oyaide as well as soon as funds allow. There is simply something very right about this wire.