If anything I would get rid of the Pass amp and get an amp with a lot more power, say 200wpc. The Pass's 25wpc is really limiting the dynamic capabilities of the Sonus Faber speakers!
Good grief.
Pass Labs specifies the XA25's output power as 25Wpc into 8 ohms and 50Wpc into 4 ohms (both equivalent to 14dBW). However, as you can see in figs. 4 and 5, the amplifier exceeded its specified power output at the clipping point, which we define as when the THD+noise equals 1%. At that THD+N percentage the XA25 delivered 80Wpc into 8 ohms (19dBW) and 130Wpc into 4 ohms (18.1dBW). It appears from the shape of the traces in these graphs that Pass specifies the XA25's power as when the THD+N is close to 0.01%
https://www.stereophile.com/content/pass-laboratories-xa25-power-amplifier-measurements