I own a close relative, the SA-201. It's an excellent amp. I haven't had any problem driving speakers with it, but mine are not difficult to drive.
Plinius uses high peak current capability to handle power demands rather than the doubling down strategy that many amps use (I don't know how this works, I'm not electronically knowledgeable).
My manual states that,"the total average impedance load for each channel should be within a range of 4 to 8 ohms. The amplifier has a high peak current capability, so impedance dips down to 2 ohms can be accomodated."
A review in HiFi+ commented specifically on the amp's ability to control speakers and "play loud without losing the ability to allow music to communicate."
Hope this helps.