Smart move. You eliminate the purchase (and shipping costs) of a chassis, power supply, interconnects, power cord, etc. Everything stays in place inside a well designed, ruggedly built, quality preamp. As a plus, the sonic signature stays the same you now have (and like).
My next suggestion? Start with a *nice* moving magnet cartridge and take it from there. I'm personally a big fan of older moving magnets, having a Sure V15 III, Audio Technica AT-15S and KAB modded Stanton Groovemaster. As a matter of fact, I'm sending Kevin of KAB a NOS Stanton Trackmaster I of the very early production runs I snatched in eBay ($54.95). It has half the coil windings of subsequent production runs and once revved up will deliver a performance rivalling $2K moving coils. Make this clear, that does not mean I don't like moving coils. I'm really fond of my Ortofon X5 MC and is among the best cartridges in its class. If your budget is entry level a Stanton 681EEE moving magnet will rock your world--guaranteed.
With psychic power and primal intensity,