I found a price on these that's unbelievable. I have the TSI100s and out of a lot of speakers I've had, these are the best for neutrality and aren't bright. They are very realistic sounding and have great bass for a bookshelf. Not that the bass goes low but it's realistic and not thin sounding. The imaging and soundstaging is really good as the speakers just disappear. I don't know what I'm really looking to get that would be "more" than what I have. The TSI100s blend excellent with the SVS SB-2000 subwoofer and sound as one.
I have had Infinity Reference RS2000.4 towers previously and these Polk bookshelf speakers just blow them away. The Infinity 2000.4s always sounded thin and bright but back in the late 90s when I bought them, that seemed to be the characteristic that was pushed by many speakers. I did replace the RS2000.4s with Infinity Reference RS1 bookshelf speakers as my animals tipped one over and it died. The RS1s suffered with a 1/2" polycarbonate tweeter compared to the RS2000.4s 1" silk dome tweeter. The RS1 also had a 5-1/4" woofer while the RS2000.4 had a 6-1/2" woofer. Even so, I didn't really hear a big difference going from a tower to a bookshelf in soundstage, imaging, or presentation. While I did hear difference in tonality between the speakers, I didn't hear any thing that would make the tower speaker sound bigger. Even at loud volumes, the bookshelf did well.
So my question, other than getting more bass output and lower bass response, what else would I gain going to a TSI400 tower speaker over my TSI100 bookshelf speaker. The TSI100 is a 5-1/4" woofer above and a 1" soft dome tweeter below. The TSI400 is a MTM design with 5-1/4" woofer above, 1" soft dome tweeter in the middle, and another 5-1/4" woofer below. Then another 3rd 5-1/4" woofer below that other 5-1/4" woofer. Sensitivity is close so output shouldn't be a big difference.
Thanks