Summary: I had wanted the TSi500, but went for 1 model down. I had thought they were identical except for the 500 having one more speaker. Turned out the 400 had smaller drivers in a narrower case. The sound has a clear high end, good solid midrange and a solid bass thought a little weak. Am thinking of adding a separate base driver. Over all I am happy with the purchase. I am using with a 100 watt low end sony receiver.
Summary: I purchased a pair of TSi400's about 2 months ago to upgrade my AV system and replace a pair of B&W bookshelf's (DM600) that I was using for the front speakers. As a test, (before I placed them in my AV system) I put them in place of my old Boston Acoustics A150's that were attached to an old Denon DRA-375 amp (60 watts/channel) driving a 2 channel stereo system in my living room. They sounded great! Much better than the Bostons!
Summary: My primary use for the Polk TsI 400's is to add more punch and range to my home surround system. I looked for a pair of fronts that would complement my Polk RM705's. I re-purposed an old pair of Bose 501's as the fronts to make a 7.1 system, but the old-school Bose set I had, albeit, are great as dedicated 2-channel stereo music drivers, were not designed to complement the range of audio needed for the subtlety of theater surround systems.
Summary: I live in China and prices are about double or more on HIFI speakers here. This made me reconsider my budget quite a bit when choosing speakers. Finally, the setup I went for is: Polk TSi 400 in Front, CS10 Center, OSW3 rear surround, PSW111 subwoofer. This is powered by an Onkyo Tx-NR709. Inititally, the TSi 400 did not deliver a very impressive sound. They literally needed a break in period like many reviewers also mentioned in forums.
Summary: First I should make it clear, I am not an audiophile. I bought these Polks to replace a pair of 12 year old JBL northridge series floor standing speakers. The polks are half the size and sound twice as good, at least to my ear. I'm using these as part of a 5.1 surround system and also for regular music listening. Love them, would buy again.
Summary: I ordered two of these for my rear 5.1 AV speakers. I have two TSi 500's Polk Audio TSi500 Floorstanding Speaker (Single, Cherry) for the front, a CS20 Center Polk Audio CS20 Center Channel Speaker (Single, Cherry) , and a 12" Kip Sub Klipsch Synergy SUB-12 Subwoofer Speaker (Single, Black) to imitate what feels like an earthquake. All this being pushed by a midrange Denon AVR 2112CI Denon AVR2112CI Integrated Network A/V Surround Receiver .
Summary: I have the TSI400 (bi-amped) towers running off a VSX-1021 with CS10, FXi A4s, and the new SVS PC12-NSD sledge400 amp and this setup is absolutely amazing. I could tell a significant difference in the TSI400s after bi-amping, the low end of midrange was much improved. Of course, the SVS is doing everything under 80Hz (crossover). I ran the MCACC to get the general calibration and only tweaked it slightly to my preferred taste.
Summary: I bought these speakers to use with my TV and listen to music. They arrived in great shape and I hooked them up to a Yamaha RX-V671 amp in stereo mode. I am not an expert but they sounded great to me. I mainly bought them to replace the TV speakers because the dialog was hard to hear in a 24x20 room. I was pleased the dialog was clear and the internet music sounded great. I could hear the highs, lows and base with the speakers set in large mode on the Yamaha.