This one came straight from the bushes, I have to admit. I knew the amp was on its way for me to check out, but I wasn’t expecting to see it for a couple of weeks. A couple of well-timed phone calls and hey presto, a courier handed me a parcel weighing 14.4 kg. I have until Monday to get to know this baby, so let’s begin with a couple of hasty snapshots.

Onkyo TX-SR605 front

And here’s the rear panel with its two (only!) HDMI inputs and one HDMI output. Three component inputs, however.
Onkyo TX-SR605 rear

Right, first test: PlayStation 3 with firmware v1.80. Fed the PS3 a Blu-ray which has a DTS-HD MA soundtrack and set the PS3 to output Blu-ray audio as Bitstream over HDMI. Now, if the PS3 was able to deliver compressed DTS-HD MA over HDMI, a corresponding logo should have lit up in Onkyo’s display. Sorry, no cigar: Onkyo receives regular DTS audio from PS3. That means PS3 sends over only the DTS core, and not the entire DTS-HD MA stream. That should answer the long-standing question whether the PS3 is able to stream DTHD and DTS-HD over HDMI as bitstream. Confused? Here’s a hint: NO, IT CAN’T. Not without a new firmware, that is.

Next up, Toshiba HD-XE1 (i.e. HD-XA2, if you’re an American reading this.) Player’s firmware is the latest available in Europe, i.e. v1.5. Entered the Set-up menu’s Audio section and selected “AUTO” for HDMI audio. Two other settings were PCM and Downmixed PCM, so AUTO was the only logical choice. Here’s what Onkyo said of the following audio codecs:

Dolby Digital Plus: PCM (tested with Happy Feet)
Dolby TrueHD: PCM (tested with Happy Feet)
DTS-HD HR: PCM (tested with Chronos)
DTS-HD MA: PCM (tested with Der Geist Von Mae Nak)

In other words, XE1/XA2 converts everything to PCM and won’t even try sending compressed audio over to the amp. I have no idea whether this limitation can be lifted with a firmware upgrade or if the problem lies with the player’s HDMI transmitter. In the latter case XE1/XA2 will never be able to pass compressed next-gen audio streams.

I’ll give the PS3 one more try, this time with Dolby TrueHD. OK, plonked in Nine Inch Nails’ live BD. Selected Dolby TrueHD and unleashed the concert. Onkyo lights up a measly Dolby Digital logo, and that’s it. PS3 OSD says the track is “Dolby Digital Multichannel 48kHz 640 kbps”. Hmmm! That’s probably caused by me forcing HDMI audio to Bitstream. Let’s see… yeah, what I figured. Told PS3 to use PCM over HDMI and now PS3 OSD reads “Dolby TrueHD 5.1 Ch. 48 kHz 5.3 Mbps”. QED: instead of compressed Dolby TrueHD, PS3 sends over plain old 640 kbps Dolby Digital over HDMI. So, either there’s a DD-compatible core in the DTHD track, or PS3 decodes the DTHD track and encodes it to 640 kbps DD on-the-fly.

Regardless, these tests show that neither the PS3 nor the HD-XE1 are able to send compressed DTHD/DTS-HD audio over HDMI – at the moment. I guess we’ll have to wait for firmware upgrades, or possibly even new players for that.

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