I just want to report back after having put these things through the paces a bit.
First, they're extremely sensitive to amp signature. Using an adapter cable, I compared the balanced outs of the Lavry DA10* to those of my Beta 22. The solo DA10 sound was equally detailed, but thinner and less impactful. I found the bass more neutrally balanced using the Beta 22.
From the Beta 22, I also compared them to my XLR terminated K1000s using that same adapter cable for the JH-13s. I was surprised by the sense that the JH-13s sounded slightly faster, and very slightly more detailed in complex passages. In fact, I was skeptical enough of my own impression that I just compared the two again with a different song. I came to the same conclusion.
I do notice though, that my speaker setup better enables me to find the fundamental frequencies in a bass line from one of the songs I made. But this is true when comparing them to any of my headphones. Perhaps speakers still have a technical edge in this regard. Unfortunately, I don't have a way to use the S300id's Bel Canto DAC with my headphones, or the Lavry with my speakers. So I question the value of this observation.
*The balanced outputs of the DA10 are different, and clearly better than its front panel headphone jack. I say this after comparing them with an adapter that converts the balanced outs to a female quarter inch jack. By comparison, the headphone jack is bassy, congested, and less articulate. I first noticed this with my MD5000s. It's even more evident with the JH-13s.