It's been shown that, at least for guitar speakers, the box they're in doesn't matter at all. The entirety of the sound quality or lack thereof is in speaker itself. Of course that is only one speaker , no crossover to worry about.
This is hardly surprising; cabinet design matters for every kind of loudspeaker. Note also that electric guitars can produce a wide range of frequencies, especially once you add distortion. Distortion generates additional tones both higher and lower in frequency than those already present.
Oh man, I've got some egg on my face for this one. I actually have a guitar cabinet that has a special geometry that disperses the sound in an area instead of directionally like guitar speakers normally do, which I bought explicitly for that purpose! Despite this, I still said what I had said, a couple posts up. How embarrassing.
That's entirely untrue, particularly at lower frequencies. This isn't audiophile cork-sniffing - the behaviour of a loudspeaker can be radically altered by the design of the enclosure. Entire textbooks have been written on the topic.
