According to the manual, the output impedance of the Audio Note M6 is <10 ohms, so impedance mismatch should not be an issue.
It could be your room is over-damped, or it could be that the dealer was using different cables. I had this happen to me before when I was buying speakers. They sounded great at the dealer's showroom, but dark in my room. I checked with the dealer, and he was using silver cables. I switched to silver cables and the sound came back to life.
It could be your room is over-damped, or it could be that the dealer was using different cables. I had this happen to me before when I was buying speakers. They sounded great at the dealer's showroom, but dark in my room. I checked with the dealer, and he was using silver cables. I switched to silver cables and the sound came back to life.