Another review from an inferior "mid-fi" pretender taken from Amazon:
Very good speaker at a bargain price. Actually got mine at Fry's Electronics since they waived the sales tax to beat Amazon's price; the total I paid was $599. They definitely have that signature, non-offensive, Polk sound. Right out of the box they sounded good to my ears, but they did not blow me away either. Having owned a number of bookshelf and towers speakers from the makes of- JBL, Paradigm, Boston, Infinity, Polk, and Pioneer etc... over the years, these Polk S55 could easily compete against $1000 towers. I have had them a week now and will update my review if needed. I have had them paired with my HK 3490 stereo receiver, Onkyo TX SR604 AVR, and Yamaha RXV 673 AVR, and the S55's sound really good with all 3 receivers. It's too subjective to say which receiver they sound better with, but they are incredibly sensitive speakers and do not need a lot of amp power.
Using 1- 5 stars, I will quickly rate the Polk S55's in these categories for the price-
Build quality *****
Stereo separation ****
Imaging and transparency ****
Treble *****
Mid-range ****
Bass ****
Volume and power *****
My rating and comparisons were based on other $300 - $1200 dollar speaker sets.
Update 03/19/17:
Even more impressed after extensive music listening. I wanted to see just how magical these speakers were. So I went out to Fry's Electronics and bought a Yamaha Aventage RX-A1060 for $730 with a promo code, then used the $470 I saved and bought a NAD C316BEE integrated amp! I will admit, I'm a mid-fi audio nut. Both great amps geared toward different audiences, I went mental with the S55's, and witnessed impressive sound stage and tighter bass with more depth. Tested both with music and movies and fantastic sound considering the price and well beyond. I am not a bass freak, so these speakers are more than adequate for me without a sub. However, you will still have a crowd whom needs more bass.
If you're strictly a music purist, the NAD C316BEE is one wicked little amp that has really impressive dynamics with the S55's, more than my other amps. I would buy this amp, plus the Yamaha MusicCast WXC-50 as a preamp (lots of features) and not look back.