Cayin a-50t vs. primaluna prologe one

Hello,
So, yesterday I had a chance to listen to a Cayin a-50t. I loved the sound and would likely not hesitate buying it. However, I have read, somwhere, that the Cayin a-50t and the Primaluna Prologue One are basically the same amp, as they have very similar specs and are made by the same parent company (Spark I believe). However, the one spec I noticed to be dramatically different was their weight. The Cayin weighs in at 28.6 pounds. The primaluna weighs in at 37.5 pounds. Maybe I'm just old fashioned, but presuming primaluna isn't just loading their amp with lead, where is this extra weight coming from? Is it possible some higher quality parts are used? Anyway, any commentary between these two amps would be welcome.

Thanks,
Patrick