how much power

No problemo. I used a Kenwood integrated for a while...with MG-1s. This was quite a while ago.

As to 150 watts and 45 amps? That's about 3.3 volts. Clearly something doesn't add up.
My panels are fused at 4 amps for mid/tweet. Figure 8 amps full tilt for the whole enchilada. Why would I need 45 amps? My Ice amps have some wacky spec like that which is IMO, nearly meaningless.

I would suggest that some scheme like this....linked, is a good place to start in any chat about amplifier REAL power into REAL loads.

http://www.audiograph.se/Downloads/PowerCube_12p_brochure_complete.pdf

Onemug,
Impedance being fairly flat is only one key to Maggies being an 'easy' load.
Second is line source. They couple very 'efficiently' into a room and don't drop level as rapidly as 'box' speakers of conventional design. The difference is not subtle
Third is phase. They don't have any of the wacky reactive behavior of some speakers which are at higher sensitivity.

Than again. some amps while measuring well into a resistor, do poorly with some types of reactive load.....be that capacitive or inductive.

To properly characterize a speaker as good/bad from the electrical load aspect, you need the phase data as well. Look up ANY of the stereophile speaker tests and they'll have such data. Any speaker with a big dip in impedance AND a high phase angle will be 'red flagged'. The warning will include advice to 'get thee a good amp'.

Personally, I guess I'd fall on the 'amps is red herring' side of the fence.
Pass is the only amp manufacturer who lists VOLTS and watts. I also suspect his amps are nearly stable enough to either weld or charge batteries.
Audio Critic? I'll go have a look.
One thing to consider is Safe Operating Range of any semiconductor device. A power transistor, even with bigtime heat sinking can only take so much.
This is a wiki about SOR and explains it better than I can. To raise the stakes, multipe devices are paralleled.
http://en.wikipedia.org/wiki/Safe_operating_area

As near as I can figger', discussions like these really end up being about power supply.....mentioned or not.

whichever you prefer. I wouldn't let an amps amps decide anything for me.

Someone needs to tell me how an amp can peak 45 amps and NOT drag the powersupply down to a low voltage, regulation or not. Even if you dump a huge capacitor bank, you than must contend with 200 watt transistors above designed limits.

power is watts, = volts x amps

Unless we are going back to the days of IPP (instant peak power) a scheme whereby an amp with a door bell size transformer can be said to have 500 watts.

As for doubling up? This is 'the law' for panel speaker users, like myself. howver, I'd rather have an amp with 400 watts at 4 or 8 ohms than an amp which doubles up from 100watts @8.

I think NAD may be on to something with continuous ratings being the same across impedance, but an ever increasing dynamic power as impedance drops. No mention ever of 'amps'.