A30 with a 3808CI

Remember the receiver (any receiver) displays what it "see".

Your player (A30) internally decodes DD+ and TrueHD to multi channel PCM.

From the player's point of view it is taking a disc with DD+ and decoding to PCM then transmitting the multichannel PCM to your receiver.

From your receiver's point of view it is receiving multichannel PCM by HDMI so it displays that.

The next question you are going to ask is how/why do some receiver's show DD+,TrueHD, DTS-HD on the display?

You need 3 thing:
1) An HDMI 1.3 receiver needs to internally decode the track (i.e receiver not player gets DD+ and decodes to PCM).
2) An HDMI 1.3 player needs to output the raw bitstream (no decoding). Only the HD-XA2 and HD-35 support bitstream out.
3) The player needs to be set to bitstream mode (not internal decoding to PCM).

From a quality standpoint in both methods your receiver's DAC are doing the converting to analog. Decoding in player = decoding in the receiver.

Long and short of it: With an A30 your receiver's decoders will never be exercised when watching an HD DVD (there's a small caveat to that statement, which I won't get into). You must rely on the player's decoding. As others have pointed out you will get the same or at least similar sound either way.

Passing the unmolested bitstreams to the receiver for decoding is a feature of the A35.