I own Arros and run them with a 35 watt tube integrated. I would definitely get something with more power if I were you, and pay attention to the amp's ability to drive 4 ohm speakers as others have mentioned.
Actually, if I planned on keeping my Arros for a few more years I'd probably upgrade to something like a Plinius 9200 or Unico, as I've noticed the Arros really benefit from some extra power and an amp that increases output into lower impedances.