The SLC-A300 drives all speakers superbly including exotic speakers with difficult crossovers, such as ribbon and electrostats.  Frequency response is flat to ten times above and below the limit of human hearing.

Speaker Warning: Cone speakers lose their flexibility with age. The powerful bass of the SLC-A300 may tear older speaker cones. Speaker damage can occur before your hear distortion.

See Ask the Professor - Wide Frequency Response

Golden Ears: Look for speakers with very wide frequency response and a very large sound stage such as Magnepan MG 3.6.  Speakers with high SPL ratings are also fun to listen to on the SLC-A300 due to the dead quiet background noise and wide dynamic range of the amplifier.