The conventional wisdom on the value, I believe, is 1/10th of the imput impedance of your power amp (which you don't state). However, I've used 10K ohm passives with Pass Aleph 3 power amps, input impedance 23K ohms, and had no trouble. A bigger factor is the quality of your CD player output stage. I'd be inclined to try passive operation befor cutting up any interconnects. Get two pairs of RCA jacks and four resistors, a good brand being Holco. (The Parts Connection can supply all these items, as can many others.)
Build a simple fixed attentuation network: if you want to know how to choose resistor values for various attenuations, contact me and I'll say more. This experiment will tell you whether your CD player is up to being used with a passive preamp, and if so, whether you like the sound. I very much do myself, and will never own an active preamp again (except for a phono preamp for the tiny signal from a cartridge).