addendum to the below: after reading your later post, if you decide to go in ear, I would tell you that for me the in ear se215s work excellent for me, acoustic guitar, electric guitar, bass, drums, vocals and keyboards all come thru clear and defined. I may have to give some credit to the sound guy at this point!

original response...
For a larger group I use the shure se215 in ears thru an Aviom/berhinger powerplay type personal mixer setup. It is really nice. But for the single, duo or trio I skip the in-ears and use the Bose Classic l1 or more often the very straightforward Fishman sa 220. For the small to mid size rooms the Fishman works very well for us, placing it a short distance between and behind us, it is our monitor as well as PA. If the room is larger I use the Bose or run two of the Fishman sa220 units, connected to each other via crisscrossed monitor in/outs, which double the amount of inputs I can use and fill things out in the room pretty well for the type of things we do. Best of luck with you duo. Please let us know how things work out with the technology.

Last edited by PatrickH; 11/10/15 05:06 PM.