Nice work! +T
Digifish performed a test recently comparing the stock R-09HR with good, quiet mics and a battery box to the same mics feeding through a Sound Devices MixPre. The benefit of the preamp (which costs $650) was immediately apparent.
http://taperssection.com/index.php/topic,105893.msg1443847.html#msg1443847
Flintstone
Downloaded, 12 dB amplified, and auditioned the ticking clock test agreeing this comparison reveals lower noise and less complex, more 'damped' ticking sound using the external preamplifier. This helps confirm my own 'chimes test' impressions the internal deck preamp is adding audible colorful artifacts not heard when deck's LINE input is fed by a more accurate preamplifier.
However, when we do these types of tests, we must be careful of test variables from mic powering/input loading effects,
and any mic placement variations.
One thing noticed from viewing digifish's photos of the test setup was the internal preamp mic placement showed the mics
more distant from the clock, and each side-by-side mic showed more distance from each other than during the external preamp setup.
While seemingly a small difference to the eye, the very sensitive-to-mic-placement nature of this clock tick test makes me think variations seen in the photo of mic placement skewed the results a bit. Audible impressions favoring the external preamplifier's lower noise may in part be due to having closer position mics=better Signal-to-Noise (S/N) results. This is of course assuming the photos are accurately depicting actual test conditions.
The side-by-side increased mic spacing during MIC input test also affects the audible ticking sound character.
Even with mic position variations, I think the generally agreed benefits of using an external preamp findings still holds up.
However, suggest next time doing a clock test like this is to both
tape down the clock AND the mics so nothing is moved by changing cables/external gear between tests like seems happened with this test.