Turntable, Two Arms, Stereo and Mono: Is your system ready for 2 phono???

Thanks to help here, I successfully am set up with big Victor Plinth, 2 arms, mono and stereo ready to go. Love it.

I realized how lucky I was that my old McIntosh preamp has 2 phono inputs, so I just plugged the 2 arms in. (In my enthusiasm I hadn't considered where the 2 tonearms would go).

I see an opportunity to buy another plinth, move my stuff to it, and end up with a second two arm setup fully ready to sell (only reason I would do this: I would end up with no extra holes in my armboards).
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QUESTION: I'm wondering how many people who might be interested are likely to be able to hook up 2 phono without buying another phono preamp.
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If I supplied an inexpensive pre-amp for the mono arm, then mono could go to any spare line input. This setup with an in-expensive preamp???

Thanks for any insight you can give me,

Elliott