Before you go ahead and hide speaker wires in the wall, set up the system with the wire and length you have in mind, and see what it sounds like.
I think you will find that 25 feet is not a good idea for speaker cables, regardless of the brand or model!
You are better off placing monoblock amps near the speaker, and running long interconnect cables. However, many preamps will not drive long interconnects- really the only way to do this right is to go to balanced line operation between the amp and preamp. Compared to the long speaker cables, you will hear an instant improvement in clarity, detail and bass impact.
Balanced lines, if set up properly, can be run to any length and the cost of the cable has no bearing on the sound of the cable, keeping in mind the caveat I imposed at the beginning of this sentence. By that I mean that if you have them set up right, 100 feet will be no problem and your investment in the cable need not exceed $300 for both channels.
The Sashas will totally tell you what I am talking about- this is not a subtlety!