When I first started to play around with the Rhea, I liked the all Telefunken route. It was good enough to convince me that I needed an IO which I did purchase.
I did find another tube set I like better and it's cheaper to boot. In the first gain stage (v1 & v2), NOS EI's from vintage tube service. In the second gain stage, GE black plate 5751's and for V5, a Telefunken 6DJ8.