i use a Radial JDV mkII ..it's a discrete, Class A direct box.. somewhat pricey for those of us on a strict budget but worth every penny (
www.radialeng.com). i plug the guitar directly in to this and use the Thru output to feed a Line6 POD Pro. then i record both the output of the Radial D.I. and the direct recording out of the POD Pro. the POD Pro is really only a reference sound.. something for myself, and/or the player i'm recording to listen to while tracking.. i get the performance perfect using this set up... this works for me because in my situation i often need to track and spend time perfecting a performance during times that it's not very cool for me to be blasting an amp (such as late at night when others are sleeping). then, once the performance is tight i can reamp to one or more amp/mic/cab set-ups as dictated by whatever sound i'm ultimately going for.
The point of using a really high quality direct box is to get as true of a representation of what is coming directly out of the guitar's output jack as possible so that later during the reamping process you won't be able to hear a difference from the D.i. track going into the amp, or the actual player playing into the amp. i do an A/B comparison to make sure all is well,... usually.. but the bottom line is the sound must be good.. whether it sounds the same or not...i just like to hedge by bets.
for reamping i just use the same box Andy does when micing one amp/cab.. the John Cunibertti Reamp (
www.reamp.com) ... it is excellent and worth every bit of the about $240 US it'll set you back. For micing more than one amp/cab i use the Radial JD7mkIII (
www.radialeng.com).. this is a marvelous box with a built in "reamp" type input (plus a cool "drag" pot for getting your input impedence optimal for your particular pick-up)... every output is Jensen Transformer isolated.. just make sure the very first amp you plug in to your AC has a 3 prong grounded AC plug and is plugged into a properly grounded wall AC jack.. then the other amps/ modelers/ effects. etc. that you plug to any of the JD7's remaining outputs needn't even be ones with 3 prong grounded plugs... no worries.. and NO HUM..... just mind your phase between all the mics... and for that matter between mics and any modelers or direct recording devices you may have on one of the other ouputs as there is often an internal latency to those buggers that is unnoticeable mostly when listening to just the device's output, but that will cause it's output to not necessarily be 100% in phase with any mic'd amp/cab signals you are capturing at the same time. Works for me because if i or the gutarist i'm tracking wants to layer amps, this box handles it with a vengeance.
reamping is brilliant.. record your tracks in relative quiet and then set up your amp and get the mic placement right... and hit record....one pass for each separate rhythm performance and your done!!
As Andy said..it's a good idea to insist of D.I. tracks for all the guitars when ever mixing for someone else... a key point though.. make sure whoever records the project in this situation doesn't edit out the noise in the breaks before sending it to you.. especially if they render the files before sending them to you (you won't be able to "draw" the region back out and regain a lost transient or decay)... trust me, you should reamp before that D.I. track is touched. they will need to punch in with the D.I. every time they punch in on their "real" rhythm track.. but that's it.
hope this is useful to some of you