The RX-V577 has the following differences/advantages over the RX-V575:
1. Extra Bass even even with small speakers. (Bass Button on Remote for easy access.)
2. Internet Radio Bookmark. RX-V575 bookmarks had to be done on vTuner's web page.
3. Access to Spotify internet radio.
4. Apple Lossless audio playback.
5. Gapless playback compatibility allows play without interruption.
6. HTC Connect™ for music streaming from HTC Connect™ compatible smartphones
7. Background Video feature (for Radio/USB/AUDIO/AUX input). RX-V575 had Radio only.
8. Audio Delay for adjusting Lip-Sync (0-500ms). RX-V575 was 0-200ms.
9. Virtual CINEMA FRONT provides virtual surround sound with 5 speakers in front.
10. RX-V477 does not have the Preset Remote unit feature.
11. Easy Wi-Fi setup i.e. iOS Wi-Fi settings sharing, WPS etc.
12. Wireless Direct connects a mobile device directly without home network
13. The RX-V577 has AV4, AV5 and AV6 Analog/Composite video inputs.
14. The RX-V575 had AV4 Optical, AV5, AV6 Analog/Composite video inputs and a Audio Analog input.
15. The RX-V577 has a Front VAUX Stereo Mini analog and USB 5V-1A input.
16. The RX-V575 has a Front VAUX Composite Video input, Stereo Mini analog and USB 5V-2.1A input.
17. No iPad playback support. It will charge it however.
18. RX-V577 has no MHL Support.
19. Option to change the volume scale from -80 to +16.5dB to 0.5 to 97. (RX-V377 to RX-V577 Models only.)
17-1/8” x 8-3/4” x 12-7/8”
17-1/8” x 6-3/8” x 12-3/8”
Power Specifications are the same:
Rated Output Power (8 ohms, 20 Hz-20 kHz, 0.09 % THD, 2 ch driven)
Rated Output Power (8 ohms, 1 kHz, 0.9 % THD, 1 ch driven)