So I reinstalled jessie on my phat dac and speaker phat and installed the hifiberry dac driver manually using the simplest asound.conf possible as described by hifiberry dac install description.
So then discovered that the native hifiberry-dac driver only supports stereo output.
so then I extended the asound.conf to include a software volume and a plug and that enables auto upmix to stereo and resampling.
type hw card 0
essentially the phat dac doesn’t make clicks in same set up, but the speaker phat does make clicks. Just retouched the solder joints and still the same.
aplay does not intermittently hang anymore so not sure what happened there, could be something in your install routine, could be me removing the vu meter alsa config, certainly a lot of complex options in alsa configuration.
to me it seems definitely some hardware problem on the speaker phat causing it to click badly, not having another to test I cannot be sure if it is a bad single device or an oversight in the board design.
If you want to send me a revised version of the speaker phat to test then you should know who I am from my email address, I have made several purchases from you, and this is first problem I have had, so anyway, the product ideas you have seem cool, I’ll be Back!