I don’t really want to get into the whole “being is perception” debate about the proverbial tree falling in the woods. Nevertheless, I keep finding myself wanting to leave my music playing (at a modest volume) during brief absences from home. Here’s why:
My new thing, in an effort to cover as much of my music Jazz library as possible, is to play my iTunes at random on the shuffle function. While I understand that not physically being present when a particular song plays doesn’t mean, in the strictest sense, that I am listening to the song, I still wonder if there is some value in playing the song anyways.
In all of the major religions — Judaism, Christianity, Islam, Buddhism — there is some sense that the repetition of certain words has an inherently positive and purifying effect. Think about Jewish adolescents learning to recite the Torah in Hebrew even if they cannot understand the precise meaning of the words they are reciting, Christian monks chanting in Latin, Sufi trance music or even the call to prayer. Or better yet, certain schools of Buddhism have prayer wheels engraved with scripture. The mere turning of these wheels, either through by the wind or the human hand, without ever producing a sound yields positive karmic energy.
So if all of these can somehow purify the ambiance like the burning of incense, then couldn’t playing my music even when no one is around to hear it have some positive causal effect as well? Or am I, not to mention the environmental impact, burning carbon dioxide just thinking about it?
Grave Error 
I think you hit the nail on the head w/ your last sentence. Those religious folks do not need to use electricity to achieve their karmic bliss whereas you must.
The better question is whether the religious karmic energy, which is just a placebo, does the person actually fulfill positive karmic energy if it is based on a placebo?
Let’s say one smokes Oregano believing that it is weed, yet feels as if they are high. Then they later finds out that they were smoking Oregano… how does that person feel? Or what, if they never learned that they were smoking Oregano, but everyone around them knew?
Ahh, who cares.
I actually think there is something very romantic in the silent spinning of the Buddhist prayer wheels. Couldn’t Coltrane being played when no one around also be valuable in itself?