I’m running my R8 with the upgraded tube package through a pair of Tekton Perfect SET 2-10’s. I’ve had the same setup for about a year now and it’s still getting better. Music sounds more... liquid, engaging, and fills out my listen room better then it did just a month ago. Great bass, dynamics, detail, and timbre.
I can’t speak to the Prima Luna option, although I’ve been very curious about them. Truth be told I’ve ordered a Decware 25th anniversary amp just to see what all the fuss is about. My only hesitation about purchasing the R8 was about it’s longevity and customer support. They haven’t been around that long. But so far I’m loving it!