FYI ...

When I asked Axiom about the impedance issue, they said RXV3800 was not one of the models that they had tested and suggested me to ask Yamaha.

I emailed Yamaha and got this response from Paul of Yamaha:
 Quote:
We usually recommend speakers with an impedance of 6-8ohms. The RX-V3800 is capable of driving 4 ohm speakers for the front two channels but we find the best results are with speakers of 6-8ohms.


Yamaha RXV3800; 2xM80, 2xQS8, VP150 and EP350v3; Panasonic 50" TV; PS3; Harmony One; Denon 3930CI