If you are refering to the Sub loudness to speaker loudness ratio in concern that your afraid your subs will be too loud for your speakers.
This is not the way to do it. RMS is a thermal rating and does not definitivly tell you how loud the speaker/sub will be (ie 400w RMS sub is not necessarily louder than a 300w RMS sub)
Basically, your looking into the matter too much. Pick out a good sub(s) and a good pair of component speakers. If the front stage is amped than your system will be balanced and sound fine.
i recall doing the same thing back in the day. i noticed that most setup's were beteen 60-70% in favor of power to the subs. however, as stated, it depends on the drivers' sensitivity ratings and output capability. too much more than power into which to factor. but the 6-70% was my personal observation during the mid-late 90's. come to think of it, i coincidentally have 800 watts to my components and 1800 watts to my subs.