Turn Table Cable Length

At 20 feet, to say perfection isn't in the hunt is, uh, redundant. So buy 20 feet of wire. Whatever.

Wow, MC. That was so productive and helpful to the OP. You're a humble genius shines through yet again. Anyhow, for the OP, there are lots of threads here about the efficiency of interconnect cable length. Generally the shorter the better; however, is there any way you can move your amplification to where your turntable is and just get longer speaker cable?

If possible install a phono stage with balanced output close to the turntable and use 20' cable connect to your preamp line in.

What imhifman said, short run to phono amp, longer interconnect. Keep in mind, the signal coming out of the cart is very low output and after 2-3’ (maybe shorter) the signal is degrading. Get your phono pre close if you can. 

Preferable to have a shorter length from turntable to amp and longer interconnects or speaker cables. If tt is your only source than move your amp together.
G