Not sure I'm following you. Why not just get a decent phono pre-amp to replace P1? If P1 is a nice vintage pre-amp, you could likely sell it for more than the cost of a phono pre-amp of comparable sound quality.
Do you have an emotional attachment to P1? If not, let it go and simplify your setup with a dedicated phono pre-amp.
Do you have an emotional attachment to P1? If not, let it go and simplify your setup with a dedicated phono pre-amp.