Hey Charles,
Good to hear from you!
External LPS, as in Linear Power Supply, will not work: voltage rectification, filtration and stabilization is performed inside the preamp chassis. Phono-2 has more robust filtration than Phono-1. The wall wart transformer (as WC correctly emphasized) is oversized 8x for the 120V model and 16x for the 230V model, and I believe that larger ones will not offer any sound improvements.
Boris