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I must vehemently disagree with VousEsEtonnant. Do not footnote polysyllabic word unless it is technical language. James Joyce wrote deliberately incomprehensible prose and expected people to dedicate their lives to understanding them. Yes, that does mean that James Joyce was up himself but he was also right, people did exactly that. We are allowed to expect more from our readers, they don't have to get everything in the one read through. There are no words in here that you can't work out in context, and really they aren't that distant from common vocabulary anyway. Keep your integrity.

Having said that. You do have elements that work here, you are making use of poetic technique, but it also requires refinement and the use of these skills in a way that corresponds with your subject.

The end of a rancid relationship reflects off the sadistic gleam of my iPod;

I like the alliteration of 'rancid relationship reflects', and, on its own I like 'sadistic gleam', but I don't think it belongs here. It breaks the spell. The feeling I am getting from this is that you are overcompensating. I know, because I am the same way, I don't think a phrase is good enough so I put more in there. No. Have faith. You have chops. The image is strong enough on its own. It's too "busy", it splits the focus, which (okay this is where I agree with VousEsEtonnant) makes it sound verbose rather than articulate and lyrical as it should be.

each melodic note reaping a stitch from my skillful composure.

This entire line is mixed metaphors. Simplify.

The threads in turn pop with each hidden sorrow found in song,

"The threads in turn pop" is again a mixed metaphor. "Hidden sorrow" is trite and beneath you.

until the slow ballad I somberly dance to becomes a single incessant drone.

The sentence was so long, the 'until' doesn't feel like it's attached to anything, it's too far removed from 'pop'. Here would be a good opportunity to use those mad technical skills of yours to mimic the music, using assonance, alliteration, attention to rhythm and flow to make it sound like the transitions of the songs. There are moments of sibilance here, 'slow', 'sombre', 'single', 'incessant', but they are broken up with harder consonants in the words between them so the effect is lost. Read it aloud until it sounds the way you want it to.

Alas, the lugubrious overture I endure is only a preface to my own performance,

I really like lugubrious overture, that is a gorgeous, decadent phrase. 'Preface' is mixed metaphor. Just because it's alliterative doesn't make it right. It takes away from the lugubrious. "Alas, it is a lugubrious overture to my own performance".

the tempo of these memories correlated to the metronome of weeping breath.

"Correlated" is mixed metaphor, amongst the musical jargon. Believe in your own imagery, it's good enough, on it's own. If you say "It is the tempo of my weeping breath", the parallels will be drawn, the metaphor constructed. It is clever enough on its own.

But without a distilled beat, music is only flamboyant sound,
and tears are polluted saltwater if their origin is not the heart.

The last two lines always must be the crux of the poem. This is one of those things where you have to experiment with writing it a number of ways with as few words as possible, and then double, and find the balance. Make it elegant, and meaningful. Picasso said "Art is the elimination of the unnecessary." That is what separates good and great poetry.
Good work.