being in the process of finishing a 14 track demo. ive played a bit with this stuff. heres my offical view. going direct can yeild acceptable results if you really know your board, eq, etc... otherwise its a pain.
even the direct out of my mesa would have taken alot of post work to get me happy. there is something magic about speakers interacting with air. if your not getting results with a 57 theres something weak in your chain.
what my band found is the need for goog mike pre's(presonus bluetube or dbx) Behringer just came out with a tube pre for $39. also used a sennhieser little square mike i borowed from a freind.
also what are you recording to, disk, tape, etc... if your recording to disk you really need a good sound card to get results.