Sveinung,
I've run your file through Rightmark analyser, and it's in the files
area under
sveinung_rh1.png
Assuming this is a straight capture of the noise via SonicStage at
Mic High-gain at a gain of 30, it is pretty similar, if not slightly
better than the RH1 I tested. It shows the LF grumble (possibly from
the OLED) and the trace is measured in a noise BW of 22Hz so you
would have to scale the trace noise up by about 30dB to allow for the
full audio bandwidth.
At this level the gain from the RH1 is very high - you can achieve
0dBFS (full scale) with an input of only -66dBu. I was unable to
establish what the minimum level needed to drive the Motu full scale
is from their website but the HiMD is unusually sensitive in this
regard - it only needs about 0.5mV for full scale output.
If you are finding that with the mic connected your RH1 recordings
are noisy relative to those made with the motu with the mic connected
then it implies you are losing signal somewhere into the RH1. Your
mic is good and the RH1 does lose you about 3dB of noise performance,
but the difference will be noticeable but not outrageously worse. If
the comparison is between the noise level of the systems at full gain
but without the mic connected then you may need to establish first if
you are comparing similar system gains. If the Motu for instance has
a similar sensitivity to the Marantz PMD660 (1.5mV for 0dBFS ISTR)
which is about 10dB less sensitive than the RH1 then your full-gain
noise will be 10dB quieter even if the preamp input noise levels were
identical...
Perhaps you could try something like Rob's clock recordings in a
quiet location to test this?
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