I'm sitting here listening to a pair of Hedd Type 20 that I just unboxed. Not a cheap speaker I'd say. A very audible level of hiss even at 4-5ft away.
What's your audio interface / DAC, and how did you set up the volume and input gain?
The manual says
The output volume rotary switch changes the reproduction level in a ± 12 dB range. We
recommend to fine-tune the volume through the connected source like an interface,
control board, mixing board or pre-amp.
The output volume allows to match the speakers to the audio chain, e.g. lowering SNR or
THD. The default setting is 0 dB.
The “Input Sensitivity” rotary switch levels the voltage of the analog input. It can be used
to optimize the signal to noise ratio for the A/D converter. In case of weak input signals
the gain can be added for up to +4 dB. In case of very loud signals (>2 V) either -4 or -10
dB gain reduction can be applied to avoid an A/D converter overload.
It sounds like nominal max input levels are +4 / +8 / +12 / +18 dBu, for 120 dB SPL a pair out (so 117 dB per speaker). If your source isn't the lowest-noise one in the world and you don't need extreme levels, you may want to turn down input sensitivity even more than absolutely required.
Once input sensitivity is in the right ballpark, adjust volume so that you get a decent but not excessive amount of headroom at normal levels (I'd shoot for ~30 dB of source volume to spare).
If none of all that gets hiss to manageable levels, you're probably SOL. (In which case I'd return them for some KH310As, which should only be marginally more expensive.)
I was expecting less noise given that it is a more expensive and newer speaker design.
That's not how this works. DSP speakers are generally harder to get quiet than their all-analog cousins since you have the additional limitations of ADC and DAC dynamic range to contend with. Higher attention to level management is required on both the speaker designer and user.
Plus, the HEDDs are officially designated as midfield monitors, which I would translate to a typical listening distance of 1.5-2.5 m or thereabouts, so 4-5' is rather on the low end to begin with.
You didn't say what your room treatment is like either. That makes a substantial difference in how fast levels go down with distance, including internally generated hiss.