50' speaker or 50' interconnect?

...btw, 50' Mogami 2534 mic cables can be purchased from several retailers including Guitar Center. They can be returned within 30 days for a refund.

If you used cheap 50 foot XLR and did not try a LONG break in you are not getting the results possible.
The minimum quality would be the Mogami (not a copy!!) suggested above. The minimum 'audiophile' 50 ft would run you about $1,000. or so (so I WOULD try the Mogami and use it for at LEAST a month or two)
I use a Kimber Hero 7 meter ($700 plus) XLR (half your distance!)
To get a speaker cable that can go 50 ft is going to cost a LOT more for the same quality.. so stick with the XLR IMO.

Ocos speaker cables are supposed to be good for up to 100 meters.
http://www.dynaudio.com/eng/systems/lines/accessories/ocos.php

I'm using about 35 ft of balanced Anti-Cable interconnects from the preamp to the amp with about 4 feet of speaker cable. Sounds great....no noise, big, wide, deep soundstage, etc.

If you are running balanced interconnects, you need to make sure your equipment is also truly balanced to reap the benefits of balanced. An XLR jack does not mean truly balanced, necessarily