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
Many good suggestions here, two that stand out are:

If you increase power and keep the same mass market level of product, you will hear little improvement.  Be sure to go up in quality vs. power, you will hear the difference.

You should audition a good quality tube amplifier.  Tubes have a different sound that many of us prefer.  My preference is for Conrad-Johnson products in both areas, many c-j amps are available on the used market.

Enjoy the search...
@moskaudio     

I hope all of this hasn't been too confusing.  To directly answer your question... No, you do not need more power simply because a speaker can handle that much power.  You might have seen that others quoted that you have an 8 ohm speaker that is rated at 88db sensitivity.  What that tells us is that you could get away with as little as 30 watts per channel, if the amplifier is built well enough to give you that full rich sound that you seek with higher power.  One thing that I have found is that on lower priced items, that it does require more power supply to create more power, so because of that, more powerful amplifiers can often sound better at low volumes,  but overall, If an amplifier is well designed, then you don't necessarily need much. Your Yamaha is a fine receiver, but it is not in the realm of good audiophile equipment. With that, I might recommend a good receiver like maybe an Outlaw or maybe a 50 to 100 watt integrated amp, a used Audio Refinement or Arcam would do a great job.... There are a ton of good integrateds.  If you like that Idea, you'll get plenty of suggestions.  I've heard your speakers, set up properly with good amplification they are a very satisfying sound.  I hope this helps, Tim 
How happy are you with the sound of the Polk/Rotel combo? 
If you are not yet satisfied; I'd try 'better' speakers with the Rotel, first. 
I'm talking only about 2 channel music here.
I had a Rotel RX-1052 powering old Boston Acoustic T-830 acoustic suspension speakers. That combo sounded great at low volumes. I later upgraded to Canton Ergo 1002 DC bass reflex design larger towers. They need to play quite a bit louder to get everything out of the music. Both are rated at 90 dB @ 1W @ 1M, but the Cantons actually play louder at the same volume setting.
Tim,
We have a similar assessment of moskaudio's current audio system. The speakers are pretty decent and will respond to better quality amplifiers. The Yamaha receiver is the relative weak link in this system. Evidence is that  lower level sound quality improved noticeably when the Rotel replaced the Yamaha. I do believe that moskaudio has recognized the necessity for moving toward a amplifier of "higher quality ". There’s more potential with the Polk speakers to be gained.
Charles
Hello moskasudio,
   Let me start of by stating that my technical knowledge can be fit into a thimble,and still have enough room for a thumb!  That being said,how large of a room are you listening in? Also,how far are you seated from your speakers?  That information should be quite helpful. 
      
       Ray