150 wpc vs. 100 wpc is not a problem.
From a perspective of how much louder 150 watts is than 100 watts, its only 1.8 dB (1 dB is roughly the smallest incremental increase in sould pressure level - loudness - that can be heard, so this isn't much at all).
And its always better to push excessive amounts of clean signal through your speakers (that isn't distorted) than a much smaller signal that is distorted (clipping is the typical example). Clipped signals forces the driver to suddenly stop/start/stop/start/etc. which generates lots of excess heat that can easily melt voice coils.
I will be picking up a 150 wpc Arte Forma I-150 integrated amp (just like you) for $2,800 speakers that are rated for 27 watts continous/40 watts peak exactly because I believe in this clean/distorted issue and I believe that speakers sound best when under a commanding grip of a beefy amp.