I know it was said waaaayyy earlier, but the point about people DI'ing and mic'ing a guitar amp with the thought process that "meh, i can reamp it later" and then not spending the time getting the amp sound right through the mic is an issue that i keep seeing more and more of and really grinds my gears. It's like autotune; just because you
can doesn't mean you should
rely on it. Don't get me wrong, i am one of those guys who captures a DI as well as a mic'd signal
just in case but i can count on both hands the amount of times i've reamped a guitar in the last 10 years, and most of that has been with amp sims to either replace or, more commonly, just blend in with the mic'd signal. It's just my opinion, but i can't help but think that if you go into these situations with the mind set of "we'll just reamp" then you may as well just have DI'd your guitar, done away with the amp, and saved yourself a shed load of time and hassle. Or, in a less cynical way, DI the guitar and have it playing through the amp just not mic'd up so you can get some feel whilst playing.
That's why a reamp box is beneficial, or at least running the line level through a buffered pedal for the quick and easy route. There's all kinds of ways around it. But just running straight line level into the amp can be noisy and it's just fundamentally not the right way to go.
Gregs comment caught my attention because that is my experience of trying to reamp from a line level turned down and then using a buffered pedal inbetween. The last thing i had to properly reamp was some tracks for my bands last album after we had re-arranged some of the songs and re-recorded the bass with a heavier tone so that our initial guitar tones didn't work. Seeing as our guitarist recently became a father, re-recording his parts were going to be very, very difficult so reamping was our saving grace. I don't own a reamp box, but i did try going straight from a line level out from my AI with the volume dropped a shed load and it just seemed to rob the amp of tone, especially in the high end. I looked at reamp boxes for a while and was even tempted just to build one (well, by "me" i mean the other guitarist in our band, he's way better at soldering than i am

) but our other guitarist suggested using a buffered guitar pedal between the AI and amp and i was pleasantly surprised at how much of a difference it made. I still don't think it sounded
right as such but it was much better than it had been and was more than good enough to get, and capture, the tone we wanted. Impedance is one of those things that i think i get until i try to explain it to someone and then just confuse myself and whoever it is i'm speaking to, so i'm by no means any kind of authority on the subject, but it seemed to me that the mismatch in impedance between the amp and AI in my situation was causing the dulled tone because the volume going in to it was as close as i could get it to just bunging a guitar into the amp.