Although all the recommendations are good recommendations, the difference as already pointed out is they are different but not better. The reason why is that the designs are similar and changes are because of the tubes used, the caps and resistors, all low end parts. IMO buy an old Counterpoint preamp and send it to me. For under $2K I will build you a point-to-point wired preamp using a better transformer, AC filter choke, better wiring, resistors and capacitors. All that will be left of the Counterpoint will basically be the chassis.
Happy Listening.
Happy Listening.