[J. FO]

"when you hear strings, they aren't in tune and their vibratos aren't matching..."
let's just say this, if it was a good chamber group, or orchestra, the strings are in tune with each other, and with the rest of the group. what you are hearing is a difference in the vibratos. so, layering strings is definitely going to help. but, if you're doing an important project, don't overlook your local music union, you'll be suprised at how many classically trained string players love to play "non-traditional" stuff.