Does altitude change the sound of speakers??

I almost suggested the OP bring the listening room along for a comparison. That's one advantage of making a cargo container your listening room; you can bring it along! Would hate to set up a rig on the long wall, though. 

OP could 3-D print a copy of old room to compare. 

Lots of science to be conducted for the benefit of humanity! 

I'll tell you what's no joke about being 1 mile up, running. Wow, that sucked, as in sucked wind, when I ran whenever I was in Denver. Incredible how the lungs burn from the elevation change. The other time that my lungs burned when working hard was without much acclimatization at Machu Picchu climbing from the complex to the Sun Gate and returning in one hour.

They could make low altitude drivers with holes in them to match the atmospheric pressure's effect on the cone. This is a genius idea and should get me widespread recognition as a futurist, because they will do that in 10 years. If you happen to live in Cleveland and buy the speaker with holes, then move to Prescott, you just put tape over the holes. If you live in Prescott and buy the one without holes, you just use a sharpened pencil to make them when you move to lower elevation. If you have a ceramic driver, too bad. This is straightforward audio, the way it should be done.  ;)

Too many variables. Temperature, altitude and humidity and seismic characteristics, to name a few.

"So if can’t hear a fart in space, can you smell one, or does that go hand in hand."

Assuming you do have a helmet and oxygen supply, you are not likely to smell it. Without it, it probably depends on how close you are to the source and how long you can stand without breathing much else.

To find your answers to these and other pressing questions, read Mary Roach, author of Packing for Mars, and other scientifically tangential books. 

Actually, it was from the first Alien movie advertised as “in space, no one can hear you scream”. I still have the movie poster.

Yes but my kid brother had the "In space no one can hear you fart" T-shirt.