Gustard R26

@soix Three reasons.  1) The Raspberry Pi endpoint might be the weak point in my streaming setup so directly connecting the LAN to the R26 was attractive.  2) The Iris is incompatible with the I2S pinout of the R26 so that mode of connection is unavailable.  3) With the X26 the Iris makes very little difference vs a USB connection direct to the Raspberry Pi.  The difference is small enough that it is hard to hear much less decide that it is better.  The only reason I use the Iris is because it "ought" to be better, not because I know that it is better.

@pinwa 

get on the head fi discussion. There are details on the I2S pin configuration for r26. In simple form people have had to short pin 15. There are other DDS units that work with r26. 

@pinwa I find it hard to believe the Iris works with the X26 but not with the R26. That makes no sense to me, nor does it make any sense that the i2S connection makes little difference over USB. What HDMI cable are you using for i2S and how long is it. i2S doesn’t work well over distance and my i2S cable is 6”. Also, what’s the rest of the equipment in your system?  Make an apples to apples comparison or this is pretty useless IMHO. 

@soix The Iris connects to the X26 through AES or Coax.  I2S doesn't work.  What does or does not make sense to you makes little difference to me but rationally the  better the DAC the less important the DDC should be.  In my experience the Iris made a big difference with the Ares II, a little difference with the Pontus II, and very little difference with the X26.  There is a guy on the Denefrips Facebook page that tested dozens of I2S cables and his conclusion was that longer is better.  

The Iris connects to the X26 through AES or Coax. I2S doesn’t work.

@pinwa Then why not connect the Iris to the R26 via AES/EBU or SPDIF?

The Raspberry Pi endpoint might be the weak point in my streaming setup so directly connecting the LAN to the R26 was attractive.

Then why not hook up the X26 this way as well? Either way at least you’ll be doing an apples-to-apples comparison. Not sure why you wouldn’t want that type of comparison.

There is a guy on the Denefrips Facebook page that tested dozens of I2S cables and his conclusion was that longer is better.

No offense to “a guy on Facebook,” but using a longer HDMI cable for i2S, assuming he was using HDMI cables, makes no sense given that an i2S signal degrades rapidly over distance given the way it was designed. If he was using USB cables that might make some sense I guess but not sure about how i2S travels through USB so maybe someone here might chime in on that.