^ Looks like VRacer was commenting on Stax bass not planar bass.
But on the contrary, I can't name a single open back dynamic headphone with more bass slam than the SR-009. In fact I can't name a single open back dynamic headphone with a single advantage in bass reproduction than the SR-009 with a great amp.
Having owned the SR-009, Audeze LCD-4, and LFF Code-6, the SR-009's bass is far superior to the Code-6's in every way except for sheer extension which in this case is actually meaningless. The Code-6 extends down close to 10 Hz while the SR-009 stops at right around 20 flat. Makes no real difference in practice especially since the Code-6's sub 25 Hz presence is super weak. The Code-6's bass is very muddy compared to the SR-009 and also softer.
The LCD-4 has amazing extension (about 10 Hz deeper than SR-009), a bit more punch, and overall a lot more heft and growl so to speak. The bass is monstrous and has very good texture and detail and transparency. But it's still veiled and almost two dimensionsal compared to the SR-009 bass.
Due to the SR-009's mind blowing transparency and resolution, you can hear so much more detail and depth in the bass even compared to the LCD-4 and it's not even close. It lifts a veil and lets you see into the bass so to speak, the texture and transparency and detail blow away the LCD-4 even in this bass vs bass comparison.
All the SR-009 gives up to the LCD-4 in bass performance is 20 Hz vs 10 Hz max extension (estimated to my ears plus the test I use is limited to 10 Hz), and overall less bass presence. The bass of the LCD-4 is always there at least subtly rumbling in the background waiting to explode, and when it does explode there's a bit more of it.
That's my experience at least. The SR-009's bass is by far my favorite and I listen to lots of bassy music such as heavy metal and rock and even rap. On heavy metal songs with extremely fast drums, that is one of the areas where the SR-009's bass performance just obliterates the LCD-4 and every other headphone I have used.
I am mildly curious about the Abyss Phi (CC) which some here have said edges out the LCD-4 but meh... a non electrostat just can't reach this level of realism so I don't really care.
And to think the SR-009 costs less than the LCD-4, Abyss Phi, Susvara, Utopia... and then there's the SR-007 with its modest price. Going from top tier non estats to a good SR-009 system seriously reminds me of going from cheap gaming headsets to good $200 open backs. Since that's when the upgrade was big enough to cause me to hear things I never heard in songs before, and when it allowed me to hear music differently. Going from even an HD 598 to an HD 800 is a smaller upgrade to me than HD 800 to SR-009.