Male and... yes, for the most part. It depends a little on the music itself, but if all you need is a generalised yes or no answer then yeah, I do.
I agree with someone's prior statement that you are going to get quite a skewed response here though - there is undoubtedly a bigger female base here than one might imagine, but it is still going to be predominantly male. If you are trying to get an idea of any statistical relationship between gender and liking heavy metal you might be better off using a sample group of 150 males and 150 female fans, instead of 300 mixed.
Also, why not use a poll? My first thought was that your initial decision to only take the first 300 responses was why (since you would not be able to limit the responses to 300 in the poll), but why limit the number of responses, especially in the same post you said you wanted as big a sample as possible. A poll would require much less reading through. And I believe it gives you the numbers as well as the percentages, so you should still be able to do all the calcs (e.g. "467 individuals volunteered for the survey, of whom 271 were male and 196 were female. Male participants were appear to be more likely to be heavy metal listeners, with 165 (61%) saying they were as compared to the 106 (54%) females fans.) Just my $0.02.