Will I improve the qualitry of sound?

Wow! Almost 3dB increase in power and no difference? What happened to better control, more headroom, less power supply strain, less chance of shifting the Q point of the transistor bias, less heat conduction from components, less power supply sharing percentage, etc.

You have to admit, a 70 wpc amp that can drive "this" load when driven by a 130 wpc is like "hot knife on butter". it is just cruising if you know what I mean.

Please, educate me! Why is it that a 70 wpc amp will not matter compared to a 130 wpc of the same amp at say, for the purpose of simplicity, 8 ohms purely resistive load and not considering any phase shift or lagging of the preamp signal driving it? Not a pissing contest but I really want to know why?

What do you feel your sound is lacking? Not enough bass, harshness, soundstage, not loud enough etc...
One thing to remember is the importance of your room and speaker placement. A $3000 system properly set up can sound as good if not better than a $15000 system which is not. Make sure your system sounds as good as possible in your room, then you'll have a better idea on what to improve upon. Swapping out gear will alter your sound but not necessarily for the better.

There are many great sites offering tons of imformation on placement and room correction, this site is not the one I was looking for but it will shed some light on the subject.

good luck!

http://www.gcaudio.com/resources/howtos/speakerplacement.html

when you mention your speakers (btw that's the only b&w i liked out of the whole line), i also figured that going from 70w to 130w won't make a desired upgrade. aim for 200w amps or add sub.