Bands That Would Sound Just as Good Without Vocalists

My wife and I were driving home late last Sunday night from the State Fair and Kamelot was in the CD player. I mentioned that Roy Khan, the vocalist was no longer with the band and that I wondered what they would do. My wife said that she felt the band really did not need a singer and that she would be very interested in hearing them without one. So that got me thinking.

What are some bands that would sound just as good without vocalists?

Here's a few off the top of my head and I would like to open this up to some discussion.

DECREPIT BIRTH
I mentioned in my review of their last album that they really did not need a singer. I stand by that. Decrepit Birth's music is technical and complex and it would not suffer at all without a singer. In fact, their singer really holds them back because he is somewhat of a one-note grunter and his vocals do not add anything at all to the music.

FLESHGOD APOCALYPSE
I happen to like their vocalist, but I really do think this band has the technical and melodic chops to go full-on instrumental. They symphonic elements would be allowed to seep into the listener's attention even more. It would be a very interesting experiment and drive that orchestral death metal sound even farther.

METALLICA
Some of Metallica's best songs are instrumentals. "Orion" and "The Call of Ktulu" are the most notable examples. Obviously James Hetfield is not going anywhere, but what would the band sound like without him on vocals and just playing music? I think it would be pretty damn good actually.

AHAB
Or really any funeral doom metal band, but I list Ahab because they are my particular favorite. This is similar to Decrepit Birth in that the vocals really do not do much to add to the music. Things would be just as depressing and atmospheric without the vocals, and indeed possibly moreso.

Anyone I am forgetting?