Hi vassillios,
Mojo is correct. All the Denon and Sherwood Newcastle AV receivers, even the inexpensive models, will drive the 4-ohm M80s without problems.
If there is an impedance switch on the rear of the receiver, leave it set to the 8-ohm setting even if you have connected 4-ohm speakers. This will let the receiver produce its optimal output and not go into current limiting, which is what the impedance switch activates if you set it to 4 or 6 ohms.
Some brands of AV receivers have hyper-active protection circuitry that will shut down the receiver if you connect a 4-ohm load, but that's not true of the Denons or Sherwood Newcastle models.
Regards,
