Two quotes from a U.S. forum of FOH techs which I feel are noteworthy, especially if you do short-cuts by using a converted cable such as--- PL plug-to-XLR plug...
"Be careful. Some balanced TRS outputs may not take kindly to being fed phantom power, if your mixer doesn't have individual switches for each channels power but you're using phantom for condensors / DIs or whatever then you could be in for some interesting, and potentially expensive, moments.
I'd use a DI."
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"I tend to like to use passive direct boxes for a number of purposes:
1. To electrically isolate the stage gear from the mixer in order to safely prevent potential ground loops, that is without using ground prong "lifters" which are NEVER recommended.
2. To isolate the destination from RF contamination that could have been picked up by the instrument and/or the cable. (MAXI, YOU WILL HAVE EXPERIENCED THIS WHILE PLAYING YOUR ACOUSTIC IN THE HIGHER FLOORS OF BUILDINGS)
3. A passive direct box provides a very high impedance load to the source, as well as a very low driving impedance to the mixer, both of which help preserve the bandwidth and dynamics of the instrument, as well as providing an impedance balanced line.
Having said this, it is important to be sure that you use GOOD transformers, such as Jensen (Radial uses them in their JDI), or Lundahl. Also Radial has some fairly good transformers in their Pro series direct boxes. This is important because cheap transformers can essentially neuter the sound of the source, leaving it dull, thin, compressed, lifeless, etc. In other words, not all direct boxes are created equal.
As far as active units go, they also provide very high input impedances, which can be helpful for sensitive guitar pickups. Power, usually phantom, is required, and they can add noise if the circuitry is not very clean. Again, quality is important." [/size]
