I don't know anything about the Underwood mods. You might want to contact this person:
11-22-06: DsremerFrom Need an Entry Level Phono Preamp
I am listening to a Jolida JD 9 with level 1 mods from Underwood HIFI which is suprisingly good for the money. I would look in that direction
Dsremer (Threads | Answers)