need to improve vocal sound

We tried to get some rough vocals down for “gold mountain” “edge” and “summerfields” so that mat knows how to arrange the music n stuff, but theres something that just aint right about how it gets recorded, and apparently its not just coz my voice and lack of talent. i think we using an sm57 mic and the marshall mg100dfx as a pre amp. There’s something on ebay that im hoping to pick up cheap that apparently acts as a pre amp and condensor, plus i think there was something about phantom power which i think is the key to our problamo. It’s not a great bit of equipment, i found it new for $80 online, but it would be easier to get from the uk, so ebay it is.