Longest Advisable Speaker Cable Runs?

More specifically, what's the longest run of speaker cables I can run off a 10 wpc amp without loosing sound quality?

Thanks guys for the replies. I've heard the baby packs a good punch-it's a tube amp and mine is class AB solid. The amp is an Altmann BYOB and speakers are modified Klipschorns with Volti Horns and Beyma drivers. Being Khorns, the far speaker is way off in the opposite corner-about 30 ft from the desired amp position.

Speaker impedance is 8 ohm
frequency is 400hz to 6khz
The type of cable is undecided - any recommendations for long runs? I've had NacA5 but that's the only cable I know of meant to be used for long runs. No idea of critical damping.

The Altmann BYOB is a pretty esoteric peice so I couldn't find much of the info you listed Almarg. I'm not sure of the impedance but it's powered by car battery so there's a lot of power in reserve. Not sure of bandwidth or feedback.
I hope that helps and I appreciate your effort here.
Dave

Byfo, The amp is an integrated with no remote, this is why I'd like it closer to my listening position-a shorter walk. It's interesting to know that Interconnects may be a better long run option for future reference.
Clio09, what is it about those cables that make them good for long runs? The shielding?
Jazzerdave and Tmsorosk, Shielded Cables with Low Capacitance is easy enough. I'll research cable companies with these attributes.
Almarg, I'd still appreciate to hear your thoughts on the specs if those gave you enough onsite to the gear and setup.
Thanks all,

Ok that's some great info. I'll look around for shielded Low & capacitance, but not extremely low. I'll also check for ratings less than or around 150 pf. I bet that will help other members in the future as they reference the blogs.
I looked at the Supra cable site and found that they're out of Sweden. That means big $$$ to me. OCOS site indicates Sumiko ownership --> $$$... Both are probably great products but do any inexpensive to mid-price cables come to mind? Such long runs are going to add up quickly on a per ft. basis.

As for the Bent Audio volume control, hat could be a fix for me so I'll check it out. I'd like to keep the system as simple as I can though. Could you post a link Byfo? I wasn't sure if Google took me to the right place.

Thanks to all,

I'll look into both those options. The Bent Audio Attenuator may be a bit to ambitious-I'm not much of a DIYer but I'll check it out. I'll also look to Sjogn for a Supra Cable recommendation and price quote. You guys are awesome. Thanks for all the help.
Dave