While I'm on a roll I'll ask one more question; What is this "line level" you are speaking of?
Your roll may have just come up snake eyes. ? Line level is the standard reference higher level signal used by all pro audio gear. Pro gear is is calibrated so that 0 dB on the VU meters = +4 dBu. In comparison, dynamic mics put out about -50dBu, electric guitars about -20dBu and semi-pro and domestic gear is usually -10dBu.
A very important concept to understand is that decibels are a logarithmic ratio, so a 10dB power difference is 10 X the power, a 20 dB difference is 100 X and a 30dB difference 1,000 X, etc.. This means that an electric guitar at -20 dBu is 1,000 times the output power of a mic at -50dBu. So a bit beyond a simple volume tweak on your guitar to bring it down to mic level. ? It should also go some way to explaining why you can't use guitar level effects in a line level FX loop.
Decibels get very complicated very quickly though, as there are (to simplify it) different types of decibels. dBu, dBV, dBm and dB SPL are all completely different things. They are essential for a real understanding of audio (and to be honest are something I have a bit of a tenuous grasp on myself - my worst scores in my training), but as a mere operator of a couple of bits of audio gear, you can get away with simply knowing the above.
Does this mean there is some other advantage to condensor microphones if their output is set to match typical microphone output levels anyway?
The capsule in a condensor mic operates differently to a dynamic and outputs even lower power by itself, so the built-in preamp is essential. Condensors are much better at capturing transients (faster, more percussive sounds) accurately and are much more efficient at capturing higher frequencies, so are invaluable for detail and instruments with more high frequency components. They usually
do push out more power (usually about -40 dB), but physical size limits the amount of high quality gain they can build into the mic itself, so getting them all the way up to line level is impractical.