8.5 + 828MkII here, too. Yes, it's difficult to get enough mic volume in the headphones straight out of the interface without turning the mix way down and the volume way up. (I don't use Input Echo because of the latency, and it's not necessary because the MOTU supports direct monitoring.)
My solution, and it's worked out wonderfully for ~6 years now, was to employ a hardware device designed specifically to solve this problem. It's made by Samson and it's called the
S-Monitor. It's basically a two-input powered mixer. Very cheap. You plug your mic into one channel and your cue mix into the other.
I have mine mounted on a short boom attached to the mic stand, so I can easily tweak the levels without moving from the singing position.
This solution only works for a single microphone, though. However, fancier devices will let you plug in multiple sources. Check out the Jam Hub products - I've not used them but they look like a great invention.
post edited by bitflipper - 2013/03/29 12:02:45