Update. It was my cable. A self made one. I bought a premade one and it worked perfectly. – So much for my soldering skills.

what is a battery eliminator ?

The Hum; I had it too and found that it can be two things; first when connecting the micpre to soundcard, you should avoid to act as a ground loop; do not touch both the xlr connector and metal parts on the soundcard when plugging in.

Hum will start when connecting Micpre to sound card, and touching both the xlr/Jack connector and the sound card’s metal parts, by that I am acting as a ground loop.

Hum will start when Overload or over peak happens, in either the sound card or the Micpre I think it is my soundcard but has to test further.

This hum does not happens when I am connecting my behringer mixer, in between the mic pre and the soundcard.