Total System Gain Question

@cleeds 

There's no way to calculate power output in watts from the information the OP has provided. You simply don't know what you're talking about.

I'm going to dip out after this. If you know the gain and the input voltage, you know the output voltage. If you know the output voltage you can work out the power required to drive a loudspeaker of given impedance, whether or not the system has the ability to drive that loudspeaker is another matter.
I try (and don't always succeed) to explain things in simple ways as people here have commented that they don't like the detail. And when I do someone always turns up to tell me I'm wrong because I didn't show my working. That is you in this case and you've resorted to insults straight away.
Anyone can look up Ohm's law and work it out for themselves, yourself included.

@pragmasi,
+1

I may be confused but if your pre-amp can put out 575mv, the amp will be at full rated power. I don't think it matters what the gain stages are. 

I had a gain matching problem between amp and preamp in my system (Pass Lab XA60.8 and AR Ref 6).  Added to this my speakers are 106 sensitivity.  Could not take the preamp volume past 7 (out of 100), it was too loud.  Loads of background noise.  Tried a set of Rothwell attenuators between preamp and amp.  Problem solved.  I don’t know if you will have a problem.  Many in this forum more expert than myself.  What I can assure you is that you can fix that problem for all of $25 (as I recall).

Just plug it in, turn the preamp up to max, wait 5 minutes, and see if you have any hearing or speakers left.  Geesh!  (The things some folks stress about!)