I've used the VOX, tech 21 sans amp, and line 6 products....they all do a pretty darn good job. The Vox unit has a tube it it but surprisingly doesn't seem to be as good as the others due to excessive noise. One of the problems with using a real amp is you need a decent sounding or dead room, and also need a mic and the skills necessary to mic the thing which is a project worthy of an entire forum. That being said, an SM57 about 2" from the grill is one of the most common ways to go about it. Experiment with setting the mic dead center and then listening with it off axis as well. In a larger room I also use an additional mic 15 to 20 feet away and then run a stereo mix with the two signals...Amp modeling has gotten really good in the past few years though. If you can afford it, the line 6 vetta II has several simulated mic and mic placement options and also lets you apply re-amping which basically sends a dry signal to your multi track machine and then allows you to route it back into the vetta on playback giving you the freedom to change amp, effects, and mic settings on playback....some other cool features of this amp are that it allows you to use two different amps at once and it also has a double track feature that is pretty cool. It's also a great amp in its own right with 2x12" celestions and 150 watts which is enough to drive 4 - 4x12 cabs and blow the house down! ..the downside is......$1600. The least expensive quality option in my experience is the tech 21 sans amp. I used it for about 10 years and was very happy with it.