Sam, welcome. As Peter said, you're the one in control of the volume, so the M80s can't overpower you in that size of room, although they certainly wouldn't be essential at this stage of your listening.
The 606 has substantial power, including at 4ohms, and you should be able to have sufficient capacity for the volume that you'd need for that room with a rather close listening distance. Unless you'd employ an extremely high volume level(capable of causing permanent hearing damage)which can shut down most amplification equipment you'll be fine.
