Hi billypratt75,

You might check the rated impedance of the Mosaics. Electrostatic speakers are sometimes notoriously difficult loads to drive. If the Mosaics present a 4-ohm load or lower, your Yamaha might be current-limiting its output to prevent overheating of the output transistors, which might explain why the Yamaha's power output seems low.

Alan Lofft,
Axiom Resident Expert (Retired)