The RSX-1550 provides virtually all of the same features found on the RSX-1560 but with a 5 x 100 watt per channel output design. If your needs grow, its on-board seven channel processing enables you to add an RB-1562 (2 x 100 watt per channel) power amplifier for full 7.1 operation. No obsolescent designs here! The RSX-1550 is a Class AB design built on over 40 years manufacturing experience. It includes HDMI V1.3 connections and the same ability to handle the new audio codecs by Dolby and dts as the RSX-1560 and also includes the same multizone audio and custom installation features. If you are considering a five-channel theater now but may want to grow into a larger system later on, this is the surround receiver for you.