[zerochief]

[size=medium] I picked up one of these on Ebay just for fun. I have to say I'm impressed when listening to a Dolby Surround encoded source.  I'm running the FX-Audio directly from the DVR analog out into the D1 analog in. It does not sound that great when a stereo matrix signal is absent. Also I popped in some LM4562's in place of the NE5532s it came with. For me it does not make your headphones sound like a 5 channel speaker setup. However it does pick up the rear surround tracks and places them in a spots "behind your head". I'm keeping this one for Dolby Surround stuff. [/size]
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Here's one of my setups. Maverick D1-A1, Alesis Nanoverb 2, and the FX-Audio. I like to add effects sometimes depending on my mood and/or the source. I can blend how much effect I want with the Nanoverb 2. Its a stereo in/out processor. When you combine the surround decoder with some blended effects it can produce an interesting listening experience. 
 
If I want pure, its there for me too.
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[size=medium] FX-Audio DAC Surround amp specs:[/size]
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[size=medium] USB decoding: PCM2704[/size]
[size=medium] Sampling rate: 16Bit 32K 44.1K 48K[/size]
[size=medium] Support Win7, Vista, XP, Mac[/size]
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Virtual surround chip: Seponix Q-Surround QS7779

 

QS7779

QSurround® Matrix Surround Decoder/Virtualizer

The QS7779 is an audio processor IC that implements a decoder for a stereo matrix encoded source material such as Dolby Surround, along with surround virtualization using QSurround® technology developed by QSound Labs. This chip also produces an enhanced stereo sound field for a stereo input signal. If the input signal contains matrix encoded surround sound, the chip automatically decodes it and produces virtualized surround sounds for two-speaker playback.

 

Features:

 

1. Dolby Surround decoder capability
2. Stereo sound enhancement
3. Center channel output option
4. Two enhancement levels
5. Parallel and serial digital interface for mode control: 
    - QS7779CM for I2C 2-pin serial control interface (Data, Clock) 
    - S7779PM for 3-pin serial control interface (Data, Clock and Strobe)
6. DC 5 to 13 volt supply
7. 24-pin SSOP packaging

 
http://www.qsound.com/products/analog-processors.htm
 
BBE Chip:XR1075
 
Amplifier chip : NE5532 (With socket,you can replace it with a better OP)
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[size=medium] Signal input: USB and RCA (auto-switching, USB priority)
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[shyamelge]

Did you notice a difference in sound quality when you changed the stock op amp to 4562? Better?
 
Does it sound good when used as a pure (without surround effects)?

 

[zerochief]

I believe the LM4562 Op amps sound better. I'm going to pop in the NE5532's back in for another comparison. 
 
It does sound good with out processing, but not as good as the Maverick Audio. I only use it when I use it for surround decoding from the Direct TV DVR.
 
BTW Its not shielded very good. if you cel phone is near (within a couple feet), you'll hear interference. 
 
It's less than $60 shipped from China so you cant expect much. However given the price its a bargain.