[Lee3]

I went from a pair of krell fpb 750 mcx's which suck gobs of power all the time to a pair of krell evo 600e's which use 2 watts in standby and my electric bill has gone down by ~ $100/month. Both pairs ran equally warm when playing music fwiw. I can't answer your question about how much running that pair of amps costs in electricity per month but it's certainly de minimis compared with the price of the 900e's. The important distinction is making sure your friend is buying evo 900e's as opposed to evo 900's if he is concerned with electric costs due to consumption in standby.