For me it was finding a tube integrated that paired well with my QLN Prestige 5's I was visiting a friend in Austria that has the QLN P 5's and was driving them with the Audio Hungary Qualiton X200. Later we went and toured the AH plant and I bought an X200 when I got back state side.
Now I have also added a couple of Class D components to the mix also and I am really loving the Bel Canto e.one REF501S with my other BC components.
Class D is almost there my friends to challenge Class A, A/B.