Heh, the dude from Mnemic is a beast. Re: frequencies below 30hz, you can (in theory) amplify them (see the [url="http://basschat.co.uk/index.php?showtopic=105059"] thread about the Prodigy's PA for some more discussion[/url]) but you need lots of power and lots of speaker area, and in practice it tends to be all mushy if you try and make it all about the fundamentals. Most of the sound of the strings is made up of higher harmonics.
To be honest, if I was playing with guitars tuned below B I would probably do as Meshuggah do and play the bass line in the same octave- trying to do the octave down thing just seems like a lot of hassle to me (although certainly possible if that's what you want).