Power consuption of an amplifier

Hi, friends!

Maybe you can help me to figure out the peak power consumption of my amp.

I have bought Micromega M-150 from USA, but I live in Europe now. The amp's voltage is 120v, but I have 230v in socket here. So, I'm going to buy a step-down coverter 230v to 120v. Each step-down converter is designed for some maximum load, 150W, 450W, 600W, 1500W etc. So I need to know how much power my amplifier consumes from a socket to choose a coverter.

The problem is that I found three different points of view:

1) The Micromega's manual says: 

Power consumption: Standby : 1W

2 channels -1/8 Pmax under 8 Ohms : 185W

The seller says this is the maximum and I should take converter with double reserve, let it be 450W

2) Hi-Fi News Lab Report says:

Power consumption (idle/rated o/p): 40W / 480W (3W, standby)

I was told in another audiophile forum that 480W is maximum. So we can take with reserve 600W converter.

3) On same forum another guy counted this way:

You should take the dynamic power for two channels and multiply it by two. It means like 300W*2*2=1200W. And as the dynamic power of this amp on 1Ohm is 690W you showd take at least a 1500W conerter.

So I'm confused... The converter I want (Krieger) is 1150W maximum available and costs too much with shipping.

Amp specs:

Power by channel: 150W for 8Ohms, 300W for 4Ohms (I have 4Ohms speakers)

Efficiency 95%

Two power supplies - one for each channel

I wrote to Micromega, but they were bought by another company three years ago and stopped support.

I hope someone here could help me with this problem.