Quick answer is it will only make a significant difference if you play at VERY loud levels. I suspect the Yamaha plays as perfectly clean as any other amp of this type. That is until you play or hit a dynamic peak that requires more than the 100 watts it can provide. Then it will begin to clip, creating minor then major audio problems as the volume gets higher beyond it's ability. Abuse it too much and you risk damaging your components.

Some will claim the separates sound better by default at any level. I'm not experienced enough to argue but I do suspect that the audible differences might not be equivalent to the investment, unless you are a loud listener and hitting the clipping threshold.

How loud do you normally play. Don't happen to have an SPL meter laying around do you? Many people are happy with fairly loud levels from their 100 watt receiver.

With great power comes Awesome irresponsibility.