Thiel Owners

The rest of the system is PS Audio DirectStream DAC, driving the Bel Canto REF500M mono blocks via Cardas Cross XLR and to the Thiel CS2.4's via Cardas Cross speaker cables. Front end includes Auralic Aries SE to DS via AQ Carbon USB, PS Audio PerfectWave transport via AQ Carbon HDMI (i2s), PS Audio NuWave phono via AQ Carbon HDMI from a Clearaudio Champion.

audiojan - nice system. I do have a reservation about the Bel Canto. The site states minimum impedance 3 ohms. Some class D amps hit a brick wall at their minimum impedance. The CS2.4 drops to 2.73 ohms at 600 Hz. I wonder if you might be running out of amp, rather than out of woofer. Might you borrow a known-to-be-bulletproof amp to see if the bass comes to life? 

I had a similar experience with the bass in my 3.7s sounding a bit weak.  I got out my measurement mic and real time analyzer to measure it and it measured fine on sine waves.  Still, it bothered me enough that when the store I bought the amp at was selling off their demo I bought it and ran two amps bridged mono.  The difference was pretty striking.  Even at moderate volumes the difference in definition was very noticeable.  I don't know if doubling the power supplies or capacitance or what made the difference but the improvement was big enough that I didn't second guess having spent the money.  

@tomthiel, I've used Mark Levinson ML331's and Krell KAV250 with the Thiels before and the Bel Canto REF500M mono blocks are definitely better than either of those. Especially in the bass and mid-bass. I don't think it's the amp.... I can borrow a few different amps from friends and test your theory, but I don't think that's it.

@jon_5912, the amps are mono blocks already, so I'm already there... :-)

Just suggesting that particular impedance issue.