Hello -
I've owned both preamps and used the line stage only, not the phono stage. Anyway, the PV-10 is more traditional CJ tube sound - warm, dimensional, sweet, and musical. The PV-12 is probably more neutral, more extended highs, and tighter bottom end. However, it does not sound as romantic as the PV-10. If you're into accuracy and neutrality, the PV-12 is for you. If you long for the nice, warm, musical tube sound, the PV-10 is it. Also take into consideration what amp you're going to use it with. The PV-10 mates quite nicely with a neutral solid-state amp. The PV-12 would probably match nicely with a tube amplifier. I used both with a CJ MF-2300 amp and a Classe CA-100 amp with good results.
Good luck!
Raul Yan