I wouldn´t use the terratec amp.
I f you have a Thorens turntable the you will have an amplifier with an magnetic preamp phono input too.
Use this device insteed of the terratec preamp.
(every Technics,Sony,Kenwood,Yamaha,Onkyo,.. device is better, )
Terratec soundcards are a good choice but you should look for a cheap dmx 6fire lt...about 110-120 €
Don´t save the files as a compressed mp3 file...save them as a wav file. You don´t need data reduction for your problem this wiil give you low quality copies only.
Don´t believe the MP3 freaks...mp3 is crippled sound only
Eac and/or feurio will do a good job for you.