[LAU] Some new music made (mostly) with Linux -- comments on mix?

We're getting very near release for our first CD, which was mixed, edited and overdubbed on Linux in Ardour, and will probably be mastered on Linux as well. Here are some getting-pretty-close-to-finished mixes: http://lahar.s3.amazonaws.com/scratchmixes-basic/foie-A.ogg http://lahar.s3.amazonaws.com/scratchmixes-basic/ginseng-A.ogg What's giving me headaches is bass rolloff on certain systems. On the nice flat Fostex studio monitors I was able to borrow-- and which don't have any bass emphasis--, it sounds well balanced. On crappy iPod earbuds which roll off the bass like crazy, it works well too. But on car stereos or club systems which emphasize the bass, the kick drum and bass guitar are way too hot-- sounds like the whole thing was recorded from inside the kick. Not sure what to do about this. Would appreciate any advice from the experience mix engineers around. -ken