Unless the Fishman specs say different, try it without a pre-amp first. The worst that can happen is the signal being too weak. That's unlikely, as the computer's microphone input is ready for a weak mic signal. It should work fine. I'm told that a good sound card makes a big difference. I've never recorded a 'cello with a pickup, but I'd use a microphone anyway.

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"Music is a social act of communication among people, a gesture of friendship, the strongest there is."
- Malcolm Arnold.