Your recording was done with good gear. The sound is fine. I think it is tyhe mix.
I pulled the WAV file from Soundcloud into my DAW and it looks alright, a little bit compressed. The phase correlation and all look alright. One thing that strikes me is that the piano, drums, and guitar all occupy a broad section of the sound field. Is this intentional? It gives the mix a layered sound rather than the feeling of a group of instruments spread across a stage. Was this your intent? The playing and recording are pretty darned good.
Nov schmoz ka pop.