have you checked out Ehnahre? Their album is the most amazing and most extreme thing ive heard in a long time.. they refer to themselves as experimental death metal which is why im on the quest for more! haha
Arkhon Infaustus - Orthodoxyn (Blackened death done well)
Augury - Concealed (Progressive)
The Chasm - Deathcult For Eternity - The Triumph (Excellent death metal from one of the best bands in the genre)
Demilich - Nespithe (Progressive/atmospheric)
Gorguts - Obscura (This is love or hate. One of the most technical metal albums ever)
Gory Blister - Skymorphosis (Technical dm that doesn't get boring)
Lykathea Aflame - Elvenefris (Awesome album)
Mirrorthrone - Carriers of Dust (Melodic and interesting. Some black influence there too)
Wormed - Planisphaerium (Possibly the most brutal DM album there is)
You have probably heard of them but if not then as Darkened Angel said try Necrophagist, personally I love them, brutal yet melodic.
Generally for that style my first port of call would be Willowtip Records but a lot of their bands play Technical Death Metal. Still a good few bands I like (eg Illogicist, Odious Mortem, Neuraxis, Psycroptic ) are there. And yup here comes the obligatory Arsis recommendation, yes they are probably more MDM than anything else, but A Celebration Of Guilt is one of my favourite albums ever. Curious to see how their new stuff on Nuclear Blast turns out since they actually have a full band recording now instead of just James Malone and the drummer. ( who left last year ).
Himsa were once again amazing live! You all owe it to yourselves to go see them if you see get the chance to. Also saw Blessed Apostyle, Rise With The Fallen and Bleed From Within, none of whom impressed me much but they only had a crowd of about 20 or so folk so it's not really surprising. That and the sound quality was poor.
Saw them last summer at Wembley which was great. They're all pretty much past it though - Jame's voice is better than in recent years but nothing like it used to be. Lars is also getting fat and old - was never an amazing drummer but seems to be struggling with some of the tougher stuff.
Sounding quite negative but it was still amazing for me. Just the whole metallica fanboyness and seeing them in front of the Wembley crowd playing the songs you know and love... Their technical ability may have seen better days but you could tell they're obviously still enjoying themselves on stage.
Overall was excellent - simply because it was Metallica.