Hi @Robert_Bee,
If the Mytek works as expected with the direct connection + upsampling, I would suggest you reach out to small green computer for further assistance, looks like there was a typo in @agillis’s link, should be https://www.smallgreencomputer.com (bottom right - contact us).
It’s possible, but we have implemented a mitigation for the XMOS issue in early 2019 so I wouldn’t say it’s likely to be the same issue, see: