well, you're definitely right! and i believe i really need a good pair of monitors now... this is actually an issue for me because i use some old pour speakers, so i am pretty sure my mixing work is affected essentially by this.
in my mix, it seems the bass is always too strong, and there is not enough definition to each instrument. i think i should play a little bit more with different "space" settings, as pan, eq and delay/reverb...
again, thank you for your replies diki! they are useful!