The 100 watt 5150 III amps (including the stealth) do not have midi capabilities. You would need an external interface like the RJM Music mini amp gizmo (http://www.rjmmusic.com/miniampgizmo.php) and the appropriate interface cable (which RJM sells)
I'm looking to build a home/studio use wet-dry-wet config on a budget with my 5150 III 100w with matching 4x12
line out device - suhr iso line out (any others I should be looking at?)
poweramp - considering rocktron velocity 150 or carvin dcm 150
cabinets - no clue where to start here, trying...