While I have been blissfully oblivious to the on-goings of the greater headphone/personal-audio world recently, I did receive my HSA-1b about 6 weeks ago. In between other stuff, I’ve gotten a review written (just need to do proper pictures … so probably published Monday or Tuesday … and also probably the last one I’ll ever do) …
I already loved the thing with the SR1a, but this is a definite improvement with conventional headphones.
Noise floor on my unit (with 0 dB input attenuation) is inaudible with every conventional headphone (even closed-back) I’ve tried it with even in a <30 dB ambient environment (and always was with the SR1a), even at max volume*, including the Utopia, Stellia and other more sensitive/lower impedance cans.
I wouldn’t run it with IEMs, but that’s a different issue anyway.
*Don’t try to evaluate this with unconnected inputs as you will get audible noise. With inputs shorted or connected to a proper source, I had no audible noise-floor with any of the headphones I tried the unit with, including my full collection per here).