Yeah the treble and perhaps upper mids (depending on how you define upper mids exactly) is crap on every Audeze LCD to me. Despite my HiFiMan bass criticism above, I heavily favor HiFiMan sound over Audeze due to upper mid/lower treble recession ruining the Audezes. At least higher end HiFiMan headphones don't have anything that ruins them in terms of sound, nothing is awful with their sound.
I have listened to the SR-009 briefly with the Woo Audio WES, a few times with the BHSE, and of course a ton with my KGSSHV Carbon.
But what I can't stress enough is how much impact DAC has, on bass and everything else. And even interconnects. The SR-009 is so insanely revealing that it changes more with DACs and interconnects than any non electrostat by far. Going from a Holo Audio Spring DAC level 3 or Denafrips Venus to a Chord Hugo 2, with a KGSSHV Carbon or BHSE, is like a new headphone upgrade. That substantial.
So while the KGSSHV Carbon has the most and best quality bass of any electrostat amp, perhaps tied with the T2 and Grounded Grid (zero experience with those), I have indeed made my SR-009 bass light. Basically no bass impact even with the Carbon. Using a Chord Mojo as a DAC will do this, even the Denafrips Venus to a lesser extent. Even using a Hugo 2 with cheap interconnects like Audioquest Forest will make the bass pretty crappy, worse than a good HE1000 system I think.
Gotta use a really good DAC like a Chord Hugo 2 or DAVE or Hugo TT 2 I'm sure, I'd have faith in really high end DACs with a solid I/V stage (not using an opamp for I/V conversion, e.g. Audio Note DAC Signature 5.1 or Aries Cerat Kassandra). And you must use good interconnects like Kimber Kable Hero or better.
I wouldn't touch an SR-009 if I didn't intend to splurge on the rest of the system.