I did some more listening this past weekend, as I upgraded to a Panasonic dmb-bdt500 BD Player, connected to my receiver via 5.1 channel analog output. Wow! The high res soundtracks on movies really open things up! These speakers sound excellent, in my opinion. The sound stage is very open, surpassing the speaker locations. However, for the type of bass that I love, you definitely need a powered sub, which most people either have or would add anyway.
There is a lot of detail in the high bass, low midrange to upper midrange frequency. Same goes for the highs. I actually lowered the treble just a bit (may not be the speakers, as my listening area is very bright to begin with, since I got rid of the wall to wall carpeting). The low bass, from the towers, is very tight and musical, but as I mentioned, for movies, I like the sub to kick in. Speaking of the sub, it blends very well with the towers (more so than in my last set up, which sounded more boomy by comparison, with the same sub!). Everything just sounds more complete, cleaner and crisper at high or any volumes.
I watched Jack Reacher on BD and it sounded great. There's some serious gunplay in the beginning of the film and towards the end, which really sounded fantastic and energized the room. I played some key scenes from the Hulk, Live free or Die Hard, listened to some operatic tenors and pop music, etc.
The speakers sound best with classical, instrumental music, R & B, jazz, hip hop and pop rock tunes. Heavy metal sounded a bit bright and fatigued at high volumes, but that could be my acoustics. I didn't hear anything that I would describe as "muddy or dull", but then again, I don't have an AB comparison to other polk speakers set up with identical parameters.
Panasonic 2012 3d Plasma ST 50 line, 60 inch
Onkyo TXDS 787 THX select Receiver 100 watts per channel
Panasonic DMB-BDT500 BD Player, connected to the Onkyo via analog outputs
Monster Power Center
Polk TSX 550T's for the Main LR speakers
Polk CS 10 Center Channel
Bose AM5 for the side LR Channels (formerly used for the front channels, replacing an AM3 set for the rears)
Definitive 15 inch sub PF 15
Logitech touch remote
various brand speaker wires and interconnects (I only used Monster Cable to hook up the sub)
Please let me know if you folks have any questions! Also, I'd like to read about your experience with these speakers and/or how they compare with other models in the Polk line or other brands with similar prices.
I would suggest that you get the TSX 250c center channel to bring it all together. The difference between the TSX and CS is very noticeable and you will not be disappointed. I finished off my system with all TSX 110b's for the surrounds and height speakers and the uniform sound is mesmerizing. I'm very very satisfied with my investment.
My "Living Cinema": AVR: Denon AVR-X7200WA | 4K Blu-Ray: Oppo UDP-203 | Media Library: HTPC, Synology DS3615xs 84TB | Gaming: PS4 Pro 2TB SSD, PSVR, PS3 1TB | Speakers: Polk LSi-M Series: 1x 706c, 2x 707, 4x 900LS, 2x 703, 4x 702F/X | Subs: 2x SVS PB2000, 2x SVS PC12+, 5x Buttkicker BK-LFE | Video: Sony VPL-VW675ES | Amplifiers: Parasound 2125, Emotiva XPA-7 Gen 3, 2x QSC GX3 | Power: Furman Elite 20 PFi & Elite 15 PFi | Screen & Misc: 138" 2.35:1 Stewart CIMA Neve, Harmony Elite