Some pieces are meant to be a lot more powerfull I think, the part where you rap (around 0.40) There you use a very subtle guitar lick that doesn.t really fit the piece.
IN the end you start a guitar Solo, then the chorus is dubbed over it. The vocals are distracting the solo, maybe wait a bit longer with the vocals and start them in the more dying notes of the solo.
I like the different elements that you blend, at 1.20 using different percussive sounds, really freshens up th arrangment.
Fot a first mix it’s not bad at all. I think it’s possible to get great mixes out of ordinaire speakers. But you’ll have to learn them by heart and go through a lot of trial and error.
I mix on Alesis monitor one for 12 years now, and it took me years to get to know them.
To make surcical descisions I use a pair of AKG K272 headphones, not right for stereo mixing because you need the interaction between two monitors. But good enough to check the bottom end High end.
The loss of stereo image on other systems can have a lot of reasons. Maybe because you listen MP3, that compresses a lot of the stereo image to free up memory. And most consumer systems just don’t have a very good sweetspot that can differentiate the two channels. Also a lot of systems have preset EQ’s and widening presets that can bring havoc.
For now most of the problems in your mix lie in the bottom end (lack off). The overall sound is convincing, maybe a bit 80ties wetness for my taste.
Good use of riding levels and compressors could elevate your mix, make it more alive.
The vocals in the first piece, your rap and behind it the chorusline are difficult to seperate, maybe do the rap dead centre and the chorus super stereo.