I can't speak to how well the Raspberry Pi B will talk to a Twisted Pear Opus - but can say with some assurance that the I2S on the 'B' model seems to be quite clean and does not appear to throw off many of the artifacts that the original Pi suffered from.
Using both an original Pi and a Pi 'B' to drive a HiFiDigi I2S -> S/PDIF adapter feeding a PCM1794 OEM eval board driving a class A headphone amp into Fostex T20 modded phones I noted that passages which seemed congested and unclear through the Pi 'A' now played as I believe they were meant to be heard on the 'B.'
Specifically some of the moments in Mahler's 1st and 5th symphonies where the brasses blare out over the first & second strings now seem 'right' - the horns have body, and an almost 'silvery' note without being harsh, while the strings remain quite distinct both tonally and in their correct places.
There's no doubt that there is more CPU horsepower in the 'B,' there also seems to be better noise rejection, and far less cross-talk between the network and the I2S buses - with the net result that low-level passages emerge from a completely 'black' sonic background with out any sense of pre-echo, odd - almost dithered - background hiss, or an 'edge-of-hearing' ringing that the Pi 'A' would sometimes throw off.
For about $75 USD, the Pi 'B' + HiFiDigi board combo seems to be a surprisingly competent network music streamer - so the Pi B should drive the Opus DAC well if due care is used the transporting the I2S signal.
Cheers
Jim
Using both an original Pi and a Pi 'B' to drive a HiFiDigi I2S -> S/PDIF adapter feeding a PCM1794 OEM eval board driving a class A headphone amp into Fostex T20 modded phones I noted that passages which seemed congested and unclear through the Pi 'A' now played as I believe they were meant to be heard on the 'B.'
Specifically some of the moments in Mahler's 1st and 5th symphonies where the brasses blare out over the first & second strings now seem 'right' - the horns have body, and an almost 'silvery' note without being harsh, while the strings remain quite distinct both tonally and in their correct places.
There's no doubt that there is more CPU horsepower in the 'B,' there also seems to be better noise rejection, and far less cross-talk between the network and the I2S buses - with the net result that low-level passages emerge from a completely 'black' sonic background with out any sense of pre-echo, odd - almost dithered - background hiss, or an 'edge-of-hearing' ringing that the Pi 'A' would sometimes throw off.
For about $75 USD, the Pi 'B' + HiFiDigi board combo seems to be a surprisingly competent network music streamer - so the Pi B should drive the Opus DAC well if due care is used the transporting the I2S signal.
Cheers
Jim
I think you might be mixing up Pi models. A and B were both original, B had ethernet and more RAM.
Model B 1.0: no I2S (not all the proper GPIO pins were broken out to headers)
Model B 2.0: I2S
Model B+ 1.0: More USB ports, micro SD, rounded corners
Pi 2 model B: Faster CPU, more RAM
Unfortunately, I have a B 1.0, so I can't hook mine up to a DAC
Model B 1.0: no I2S (not all the proper GPIO pins were broken out to headers)
Model B 2.0: I2S
Model B+ 1.0: More USB ports, micro SD, rounded corners
Pi 2 model B: Faster CPU, more RAM
Unfortunately, I have a B 1.0, so I can't hook mine up to a DAC
Haven't looked into the DAC side, but people have BCK and MCK going on the RPi end.
https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=8496
I'm considering a combination of RPi 2.0 + Opus also, starting to look into it. Will be interested to hear how the I2S interfacing goes for others.
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