5.1 usb decoder

[Alexontherocks]

Hi all, I am looking for a good 5.1 USB to analog decoder. I am building a 5.1 amplifier system and would like to be able to use HDMI, optical, coaxial and usb inputs to drive the 6 amplifier modules.

On the net I have found few affordable options:

HDMI LPCM 7.1 5.1 Multi-Channel Audio Decoder With Amplifier

AC3 DTS 5.1 Audio Decoder USB Sound Card DAC XBOX PS3 | eBay

NEW MOCHA X-3B AC3 DTS 5.1 DIGIT AUDIO DECODER &USB DTS | eBay

Thanks!

[sergedc]

Hi Alex,

What did you end up buying?

I buy most of my equipment from China. I currently have a Yaqin MC-10l tube amp and a DAC-01A (Xiang Pheng)

The 2 last of the products you listed are chinese. One of the sellers in China advised me against your second link. If you look at the RCA plug they used, it is obviously cheap stuff. However, I still somehow expect it to be better than a 3.5mm plug of something like Creative 5.1 X-fi USB.

The Mocha seems better. The explanation is pretty explicit that it can be used with computer configure to output 6 channels (not AC3, which is actually 6 channels encoded on 2) i.e. AAC 6 channels. I asked whether your second link can do it, and they were unable to answer.

For me, the USB input is the key requirement. I heard of lot of bad things about using HDMI for audio.

Serge

[abraxalito]

I have the decoder on the second link the OP posted. Sound quality pretty much sucks in stock form - mainly due (I think) to the volume control chip on the lower board. But worse than that, when I tried the USB input it has clicks, so given your requirement is USB, give it a wide berth. On SPDIF its ok. Price in China of this model is around the $100 mark.

I think the decoder board, based on the Crystal CS49324 has potential - I'm going to do a bit of reverse engineering on it It definitely needs decent dacs - i.e. not S-D type as fitted.

[SoNic_real_one]

I had the CS49326 in a Harman Kardon receiver and it was definitelly a capable cip. CS49324 is from the same family with less decoding functions programmed in the ROM.

Implementation of USB probably sucks because USB 1.1 is limited to 16/48 and higher USB2.0 requires dedicated drivers.

[sergedc]

Implementation of USB probably sucks because USB 1.1 is limited to 16/48 and higher USB2.0 requires dedicated drivers.

>> We are talking about 5.1, so movies. What is wrong with 16/48? Is there any movie where the sound in 24/96? What is wrong with using drivers for USB 2.0?

[SoNic_real_one]

Usually you don't have those USB2 drivers, they are not native in Windows.
DolbyDigital has 448kbps while DTS has 754.5 kbit/s (sometimes the full rate 1509.75 kbit/s).
USB 1.1 audio hosts are limited by OS to 16/48kHz - that is 816kbit/sec per USB specs at 16 bit payload (deducting the overhead). If the controller uses 8 bit payload, the real datarate becomes 568kbit/s.