on the back there are balanced TRS i/o holes
really cool is that you can switch between -10 or +4 or "really hot" (probably +6 Db)
for in- or output seperately. so you can feed it a nice hot signal, and monitor that on consumer level. Ideal when using small active mixing speakers on the road. the headphones output is extra, so are 2 of the inputs on the front. the other two you can switch between back front and both. input 1 has a guitar amp emulator thingie
I've hit the limiter more than once recently,(not a bad limiter, much much nicer than the crappy one in the otherwise excellent focuswrong mixmaster) and will go for the "extra hot" on the input.
the routing is awesome, and completely programmable
timing is solid, though not as solid as the completely concrete Hammerfall series
I am completely happy, but when going for 16 channels, you can also look at the lynx that people seem to like over here...
oh and on the 800 firewire bus, you can cascade firefaces, theoretically raising the number of i/o to more than 32 at 24bit 96khz (with some adat interfaces)
currently I use a ADI-8 AE with the fireface. flawless. the G4 has to run hard to keep up.
just download the manual at
www.rme-audio.de
(no I'm not a rep)