The gender-split in audio

Are there any theories as to why audio seems to be such a male interest? I KNOW that there are some female audiophiles out there (and, of course, that most men are not audiophiles), but there seems to be a very large imbalance within the audio world. I think audio should be important to any music-lover. There are lots of women for whom music is an important part of their life, so why the gender-split in audio? As I said, I am wondering about theories, not anecdotes. For example, maybe it's all about marketing, not the accurate reproduction of music per se. But I look at my gear and some ads in audio magazines and for the most part there doesn't seem to be anything intrinsically "male" about them or how they're pitched, and I doubt it would be sufficient to account for the apparent imbalance if there were. However, maybe I, as a male(!), underestimate these factors.