You state that you are moving your phono system away from your speakers. This indicates that the rest of the stereo is staying where it is, correct? If so, I assume you are moving the phono preamp too. (If not, you should, as a 25 foot run from the turntable to the phono preamp is a bit too long, IMHO.)
As far as a cable, I recommend the Nordost Quatro Fil. I use it for my preamp to amp run (a 4 meter cable) and my friend used to use it in the same application in his system. (His was a 6 meter cable, which is almost what you are looking at.) This is a very neutral cable, with good resolution and detail, and it is very good for the price. Long runs don't seem to affect the sound much either. (The price has dropped considerably, now that current Quatro Fil owners, like my friend, are upgrading to the Valhallas, and dumping their Quatro Fils. The used price for a 7 meter Quatro Fil should be around $1,800.00) FYI: I have heard the difference between the Quatro Fil and the Valhalla, (both in my system and in my friend's system), and while there is a difference, it is so subtle, that I don't feel I am missing much by not upgrading.
I prefer the Quatro Fil to both the Straightwire Serenade and the Cardas Golden Reference that it replaced. (Although the Golden Reference was a pretty good cable too, and I would recommend that if you like a touch of warmth to your sound.)
My two cents worth.