Opera Seconda and Tubes

I have a pair of 60 watt Quicksilver monos and am thinking about the Opera Secondas. The sensitivity is 89db, but they are 4 ohm speakers. I don't know if they are a relatively easy 4 ohms or a very demanding 4 ohms. They would be used in a medium size room listening to all kinds of music. I have no way of listening before I buy. Will my Quicksilvers be enough or am I looking for trouble? Thanks.