IMO the three-wire box (or Chris' 4.7k mod) loses a bit of gain, but not much. I would guess something like -10dB or so. But it is not a problem in practice (see below).
For any reasonable level of amplified music, a minidisc mic-in/low-sens will work great. I've recorded a ton of shows with this. FYI, mic-in/low-sens on MD is pretty much the same as mic-in/low-sens setting on the Edirol R09. Both have moderate gain (around +20dB max) and a wide range of variation of input levels that will not overload (eg., from -20dBv to +10dBv). At these moderate levels of amplification mic pre noise is not usually a problem.
Problem cases are:
- recording quieter stuff, like acoustic music. You could run mic-in/hi-sens, but that is noisy, but an external pre will help.
- recording with certain low output mics, like Sony ECM-907. These are about -10dB lower than the AT stuff.
- trying to run into line input on crappy analog inputs, like iRivier, NJB3, etc. These provide a little gain, but it is terrible quality,
so all the gain should come from an external preamp.
I suspect a preamp may provide a bit nicer/cleaner gain than the MD/Edirol mic-in/low-sens inputs. I'm currently getting one of Chris' pres to check this out. But it is not really needed to get started. Consider it as a potential upgrade later on.
Richard
PS: Thanks for Chris for posting, and *repeatedly* answering the same questions. That is one reason I stopped selling battery boxes. I just don't have the patience for that. I also worry about building/servicing stuff for others. I keep worrying that it will break and I will let people down.
I'm wondering if some kind person can put this stuff in an FAQ. Perhaps a "flowchart" saying what conditions you need a battery box/three-wire box/preamp, and where to get one (links to Chris or others to buy and links to some schematics I've posted in the past if you want to build one). Sorry, I don't have the energy to do this right now.