How Long Cables From Turntable to Preamp?

I want to add a turntable into my audio system. My equipment rack is maxed-out and cannot include the addition of a turntable. In addition, the second rack for the TT can't even be next to the existing one because it's in a walkway area. So, I have to place a separate stand for the turntable about 6' to 8' away from the preamp. Even further would work better still, but..... I'm concerned about line loss or other problems with long cable length.

What is the longest possible length of cables that would be allowable from the turntable to the preamp?