Need some Amp help - a little new to properly powering speakers


Hello. 

 I have some polk LSIM707s that I thorough enjoy.

However, at the moment I'm powering them using a Yamaha aventage 3070 receiver which at 150 watts at 8ohms sounds pretty darn good. 

However, since these are rated at 300 watts at 8 Ohms, I assume I will need some more power. I notice at lower volumes a lot of the imaging and clarity disappears. 

I am looking at buying a 300 watt emotiva Amplifier, or a 500 watt emotiva amplifier.

I'm assuming it would be better to purchase the 500 watt per channel emotiva so the speakers won't suck it dry or stress it. 

Am i wrong in this assumption? 
moskaudio
moskaudio

 Impedance reaches a minimum of 3.75 ohms at 66 Hz and a phase angle of –47.96 degrees at 83 Hz.
Read more at https://www.soundandvision.com/content/polk-lsim707-surround-speaker-system-ht-labs-measures#fIW7rJB...
This indicates for them to sound their best in the bass, an amp that has good current delivery <100hz.
A good solid state amp that can keep increasing it’s wattage for every halving of impedance, is an indication that it can deliver current.

EG: A theoretically prefect amp that delivers current, none can do these prefect figures in real life, but some get close.
8ohm 50w
4ohm 100w
2ohm 200w

Cheers George
Moskaudio:  As said, it's not necessarily the amp's rated output, although higher output sometimes goes hand in hand with higher current.  High current amps and ones that have a high dynamic capability is what you want.  At "normal" levels, your used output wattage, will most likely stay fairly low, but when the snare drum cracks or the cymbal crashes, or the cannon sounds, that's when you need the headroom that a high current amp can produce.  Most speakers are not damaged due to high wattage, they're damaged due to clipping the signal.  A high current amp will always sound better than a high wattage amp made from IC chips.  The difference is night and day.  The impedance and the sensitivity of your speaker also plays a very significant role.