Your preamp may have a pair of XLR and/or two pair of RCA outputs.
The SVS subwoofer may have a pair of RCA inputs and a pair of RCA outputs.
If so, simply connect a pair of interconnects to any of the three sets of the preamp outputs to the SVS's RCA inputs and another pair of interconnects from the SVS's RCA outputs onto the Quad's RCA inputs.
Monoprice or Blue Jeans Cable can provide long custom length runs of cable at reasonable prices. Have fun with it.
The SVS subwoofer may have a pair of RCA inputs and a pair of RCA outputs.
If so, simply connect a pair of interconnects to any of the three sets of the preamp outputs to the SVS's RCA inputs and another pair of interconnects from the SVS's RCA outputs onto the Quad's RCA inputs.
Monoprice or Blue Jeans Cable can provide long custom length runs of cable at reasonable prices. Have fun with it.