Very pleased with my new 677, only issue I had was the auto set up for my 5.1 system. The amp sets up as a 7.1 and gives errors on speakers that aren't on my set-up. The level and distance errors came up and incorrect phase (it got me that paranoid I went through each speaker to make sure the wires were all correct, which they were).
The levels and distance set up you alter when you switch to manual set up then you can remove the speakers on the set up that's not in use (as I've not got them). I may have not understood the set-up process, but think I've got there in the end doing a Auto setup then tweak it in manual.
If you have as tablet or smart phone you can down load a set up app and controller app that makes it easier to use the unit.
On the whole, very pleased and for the money it's good value.