Originally Posted by bobgpsr
Will it allow you to force Dolby PLIIx on a 5.1 LPCM input to drive the back two surrounds of a 7.1 system?
No, the onkyo 604/674 will not process 5.1 LPCM to 7.1 via PLIIx (it will only process supported bitstreams).
Other deficiencies: it can only accept 5.1 via HDMI (not 7.1), and it appears to have the -10db LFE issue over LPCM (supposedly a firmware fix is working on that one).
It is still one of the better values for HDMI, though.