I'm using the same PCM5102A DAC board on a Pi B Rev2 as in this blog post with software configured as per this post, connected in the same way. The audio playback is slow but otherwise of good quality.
Audio plays at the correct speed from the builtin audio port, when configured that way.
I have since tried again with a different breakout board, again for a PCM5102A, but experienced the same problem. The problem remains whether or not I overclock the pi.
I haven't found anyone else on the internet reporting this problem - what am I missing? Is this a driver issue because for some reason the
hifiberry-dac overlay isn't appropriate, or is it a hardware limitation of the Pi 1?