The STR-DH540 features a 5.2 channel speaker configuration, while the DTR-DH740 provides 7.2 channels that can be configured with either surround back, front height, or bi-amp speaker configuration. The stated power output ratings for both receivers are 90 wpc RMS (measured from 20Hz - 20kHz with 2-channels driven at 6 ohms with .09 THD).
Both receivers also feature four HDMI 1.4a-enabled connections that provide 3D and up to 4K pass-through, and Audio Return Channel. A front mounted USB port for accessing content on flash drives or iPhone, iPod, iPad is also included. However, it is important to note that neither receiver provides addtional video processing or upscaling, nor provides network/internet connectivity.
For easy setup, both receivers also include Sony's Digtial Cinema Auto Calibration speaker setup system.
These receivers are targeted for those that have, or are putting together, a modest, few frills, home theater system.
Photo - Top Right: STR-540 Left Side: STR-740 © Sony Corporation