Fans of instrumental metal albums should do themselves the favour of checking out 'Return to the Point of Departure' from the oddly named Texan outfit Mahogany Head Grenade (Note to self: Must send them an interview where I ask about the band name...). For me, this is kind of a continuation of what Joe Satriani did with 'Surfing with the Alien' (1987), one of the coolest instrumental albums to have been made (in my humble opinion).
The thing about 'Surfing with the Alien' is that you can listen to it actively and discover new elements and layers all the time if you so desire, OR you can easily just let it work in the background and use it as a pleasant backdrop when you work, read or whatever. The same can be said of Mahogany Head Grenade's music.
The trio delivers a convincing tapestry of sound, both multifacetted and layered, but at the same time, it's something which you can just run in the background whilst working. Which I have done for some time now almost everyday at work. It's good stuff, really - I suggest you check out the band's bandcamp site.