system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why smoking marijuana enhances enjoyment of music

I know this is a subjective effect and doesn't relate to everyone who smokes.
gpt
Going from memory and not an expert and somewhat theoretical.. but

the short: It forces your brain to reroute stimulus because the usual neural path is temporarily blocked, until the drug wears off and signal receptors are no longer occupied. 

the long: 

Neural transmitters and receptors are the parts of your nervous system that act as the wiring to send tiny electrical impulses to where ever they need to go. The brain transmits signals that tell your muscles what to do, your senses send information back to the brain to be translated into sensation.  Taste, sound, touch, sight, smell. All of it is just your brains translation of the signals it receives from your senses.

Different sensations get routed to specific parts of the brain that are specialized in translating that type of sensation into your perception. Everything you experience, whether it's physically real or imaginary is processed by your brain this way.

You do not experience reality, no one actually does. We only have our perception of reality based on what our senses tell us and how our brains translate that information.

The brain is jam packed with receivers, many of them are a type called cannabanoid receivers.  

Besides THC, marijuana also introduces cannabinoids (CBB & CBD) into your system that find their way to and occupy these receptors and temporarily prevent them from receiving further input. This alters the way the brain normally processes stimulus. This is why it's also helping many people with muscular and neurological disorders like epilepsy and narcolepsy for example. It's also been shown to decrease the adverse effects of severe autism in some cases 

Music might sound new and perceived to be better, or foods might seem to taste better, colors more vivid, even stupid jokes funnier because the signal path is rerouted to a path not normally associated with those sensations. It is essentially a new and different sensation because the neurons that conveyed it had never taken this newly created path before and some of that stimulus arrived at a portion of the brain not as adept at processing that particular type of information.  

You are essentially re-wiring your nervous system to work around a shorted circuit...   Some biologists have theorized, it was because humans evolved to gain the ability to reroute these signals so efficiently if needed, that gave rise to our further evolution, of increased intelligence, a spoken language, social interaction and imagining such cutting edge inventions as the wheel or the spear. aka The ability to think "what if?" In fact some go as far as to say, if primitive man had never ingested marijuana, we'd still be living in caves.