You just want to setup a Practice room right...i am assuming not a Recording room...
U just need to make sure that u soundproof the room so that outsiders are not bothered with ur loud playing...
-Get thicker glass for windows
-Use sound absorbing material on the walls and ceiling
-Put a thick mattress on the ground
-Raise the level of drums by creating a wooden platform so that people staying below are not bothered with the bass....
Why do u want to plug everything into one amp... Use separate amps for bass..guitar..keys..Drums wont need any amplification coz they wud be sounding loud the way they are..
Guitars : USA Fender Stratocaster 1981 Collectors Series, Ibanez RG420eg, Cort X6vpr Snake skin, Custom Tele Style Guitar
Processor : Boss ME 70
Amps: Laney Cub10(4 Sale), Roland Microcube
Recording : Focusrite Scarlett 2i2, Shure SM57
For Sale: Sansamp Tri-AC