adding a preamp?

Hi, i have a question.
Currently i own a Marantz SA-15S1 CDP powered by a Marants PM-15S1 integrated amp, there is a tuner and a turntable hooked too. Speakers are B&W CM7.
I am thinking about gathering everything up through a pre amp that would be ultimately connected to the existing amp - in other words, getting a pre amp to gather up my sources and using the existing amp as a power amp. I am not sure if this is even makes sense or whether it`s going to work, but if it did, would it be worth the investment? Or should i tap some more and get a dedicated pre amp / power amp combo? This would practically mean getting a new system - least desired financially.

I am looking, like everybody else, for the perfect sound.

Thank you.
You already have a pre built in to the PM15S1. Why would you need another? Surely there are enough inputs for those sources on the PM15S1.
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If you intend on buying a separate amp later then getting a pre to start is fine. but if your plans are to keep the current amp, I would leave it alone and look at other components to upgrade. Don't know what other equipment you have but maybe speakers.