Ian I2S FIFO, QA660, Audio Widget USB, DDDAC NOS 1794 and more

[lxiaob]

1.Open-source USB interface: Audio Widget
2. Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
3. QLS HiFI: QA660
4. A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

Guys in this board should be very familiar with 1, 2, and 4, and you may not hear of QA660 from QLS-HiFi. I ordered all of those toys together recently, and played around for a while. I would like share my test and thoughts after.

 

[lxiaob]

Systems connections as blow:
1. QA660+QA100
2. QA660+NOS 1794+MG-SI15DT(tube)
3.Audio-Widget+I2S FIFO+QA100
4. Audio-Widget+I2S FIFO+NOS 1794+MG-SI15DT(tube)
5. Audio-Widget+MG-SI15DT(tube)

My speakers is Energy RC-70. After hours of listening and comparison with different music, I have some thoughts for all the combinations:
1. The digital outputs of QA660 and Audio-Widget+I2S FIFO are very very close, it's very hard for me to pick up the better one, but if I have to say, I like QA660 slightly better, because QA660 is a mature product.Generally speaking, the I2S output of QA660 and I2S FIFO are on the same level.
2. The DAC of Audio-Widget is not good, the high is rough, and low is loose, even with the tube amp, but after put the I2S FIFO behind, the whole system performance jumped a huge step, that means I2S FIFO worked very well for its design purpose.
3. The NOS 1794 DAC seems non-sensitive with the clock at all, even with the MCLK disconnected, the DAC could still work like a charm.
4. The QA100 amp is a great little Class-D amp with outstanding performance considering the price.

 

[hochopeper]

In your photos I think you could get some improvements by neatening up the wires that the i2s output of the FIFO goes via, separation between signal and it's return wire are important, especially on the output. Where do the twisted pairs go to?

 

[lxiaob]

In your photos I think you could get some improvements by neatening up the wires that the i2s output of the FIFO goes via, separation between signal and it's return wire are important, especially on the output. Where do the twisted pairs go to?

I think you are right, will do that when got better cables. Even with the current setup, the background is deep dark. The non-twisted wires that came with Ian's I2S FIFO kit are only about 10cm long, I guess the system is able to tolerant that. The twisted pairs go to the I2S input port of QA100 amp.

 

[marce]

Digital signal and its return should be in close intimate proximity, separation is bad.

 

[lxiaob]

Ordered connectors for the I2S connections from ebay,$17.5 for 10 sets, seems a good deal. I will see how much improvement can be gained from the fine I2S connections.