User manual Pioneer VSX-921-K (English - 104 pages)
Amazon.com: Pioneer VSX921K 7.1-Channel 3D Ready AV Receiver - Black (Discontinued by Manufacturer) : Electronics
PIONEER VSX-521-K 821-K 921-K AV MULTI-CHANNEL RECEIVER RRV4167 2011 SM Service Manual download, schematics, eeprom, repair info for electronics experts