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For your USE of the receiver: Some receivers DO allow HDMI passthrough when they are powered off. They generally only allow the last source used to pass through, so this is usually the cable box. I will have to double check, but I think some Denon receivers may do this right now.
It is worth asking at a store, but you really have to define your exact usage of that feature.
Otherwise, any HDMI 1.4 equipped receiver will handle whatever audio you throw at it pretty well these days.
For Denon, on their AVR-2312CI, it looks like it is called HDMI Audio/Video repeater function...
But I really don't know what that means!
"HDMI Audio/Video Repeater Function"
DENON US)
From page 68 of their manual:
"When “HDMI Control” – “Control” (vpage 106) in the menu
is set to “ON”, signals input to the HDMI input connector are
output to the television or other device connected to the HDMI
output connector, even if the power of this unit is in standby
(pass-through function)."
http://usa.denon.com/DocumentMaster/US/AVR-2312CIE3_ENG_CD-ROM_v00.pdf
Should pass A/V in standby mode, and then use the speakers when it is actually on. No guarantees on me for that though!