Kevin_video and I were emailing about such a character. He played with a guy with a Rogue/Sorcerer with Precise Shot, Point Blank Shot, WF (Ray) and Maximise Spell, possibly some others. He didn't take Arcane Trickster. It was so good the DM banned it.
How does this character get 100 damage/ray at 4 rays per round, even at lvl 20?
Taking more Rogue levels for more SA dice cuts in the caster levels, while more Sorcerer levels cuts in the SA dice.
I see using Disintegrate follow by a quickened Scorching Ray, which would yield (with a Sorc15/Rog5) 115.5 damage followed by 3x 24.5, if the target is flatfooted and subject to sneak attack. It does cost you two lvl 6 slots, though, and the Scorching Rays are subject to Spell Resistance. It also assumes he has Quicken Spell and Arcane Preparation/other means to avoid Sorcerer fullround Metamagicing.
I'm really curious. Kevin, if you read this, feel free to post here.