I'm not a huge fan of Suicide Silence's later music, but their first EP was absolutely brutal and a great release. So, I am looking for more music like that, I believe it's called deathcore. I only want vocalists that have great high pitch screams, but also great low gutturals, and use both of those type of vocals in their music. Keyboards is an added plus as well.

Example of what I'm looking for...
https://www.youtube.com/watch?v=HGFzhQJo37k

For high and low gutturals with the ocasional keys you can listen to The Crimson Armada:

https://www.youtube.com/watch?v=RZ8akbP1ki0

Not very similar to SS, but, Make Them Suffer also combines high screams and low growls with many keys here and there.

https://www.youtube.com/watch?v=5NyMGQd6BlE

I think Dead in my Arms by Carnifex is exactly what you need https://www.youtube.com/watch?v=TNxnXnBZ4cw

Hmm, have you tried Oceano? :3 They're pretty fitting of your description I'd think.

Wow, I'm liking Make Them Suffer! Thanks!

The first thing I thought of when I read "Symphonic Deathcore" was Mortal Treason: https://www.youtube.com/watch?v=iefNRnj ... re=related

Just FYI, Mortal Treason are(were) VERY CHRISTIAN. No idea if that bothers you, but some peeps are not into Christan stuff...

Also, because they are fucking awesome, Rise of Caligula: https://www.youtube.com/watch?v=HyLVU_8h4q8
Cause more people need to listen to Rise of Caligula.

Some key-orientated deathcore:

Betraying the Martyrs

By Blood and Iron

Winds of Plague

Job for a cowboy's first ep, Molotov solution, and misericordiam should be what you are looking for

Fleshgod Apocalypse

Not really symphonic but has a lot of keys and a very spacey atmosphere

Not really symphonic but has a lot of keys and a very spacey atmosphere

Substructure