Without looking looking at specs of both models i can tell you spark/cayin is same oem. I know so because i was in authorized seller in hong kong and they told me cayin is "export" name and spark brand was sold in same shop. There maybe minor spec differences for similar model....just like honda/acura. Ex. In japan there is only honda branding of cars that would be considered acura in north america.
Cayin A100T vs Spark MT-100k
Spark audio makes Cayin. They have an integrated named MT-100K under the Spark name that seems to have the same specs as Cayin A100T. The Spark model weighs about 7 lbs more than the Cayin model. Anyone heard the MT-100K ? Curious to know the differences between the models.