[PStamler]

Congratulations on the good results. The instrument inputs on some interfaces will indeed work for this, as long as there are two of them (a lot of interfaces just have one). If you plan to do this again you might want to look up the input impedance of those instrument inputs and use a Y-connector to add some parallel resistance to bring it down to 47k, which is what the cartridge wants to see.

iZotope RX has a pretty decent scratch and crackle treatment; start out with it set to about 1.2, and increase as needed.

Peace,
Paul