ProAc Response 2.5 / D25 / D28's with tube amp

Anyone run/ran these speakers with a tube amp?

Which output tap did you prefer (4 ohm or 8 ohm) and why?

I auditioned the D28's with several different amps (Class A solid state and tube). They sounded their best with a reasonably powerful valve amp on the 8 ohm tap (they are an 8 ohm speaker) - this is when they sang and the soundstage opened up. Very nice.