Muting really necessary when playing metal riff?
I wonder how many of you are able to mute unwanted strings when playing a fast metal riff (at probably 180bpm ish).
For example, there's a bass solo part in Metallica's holier than thou, and I believe it starts with an open E and then an open A. So...ideally, the other three strings should be muted somehow when playing either the open E or the open A.
In fact, I tend to let the middle finger of my fretting hand mute the undesired strings (although the E string is naturally muted with my plucking finger playing the open A). And, I just find it hard to keep the rhythm, and have noticed that the middle finger used for muting may make noise at times....noise that would not occur if not trying to mute the unwanted strings at all in the first place.
My question is, is muting really necessary when playing a fast phrase like that? Or I just don't need to pay too much attention on those unwanted strings UNLESS they're vibrating noticeably?