What I can tell is that LineIN works good so far. I figured out that there is a slight drop in low frequencies below 200hz. It's linear so a frequency of about 80hz has about 1-1,5db less gain.
What? Seriously? That is not good!
How did you measure/test this?
First I estimated this when I looked at the waveform of some low synthesizer signals below 200hz.
But now I tried to do a test wich might show it a bit better. It's "Pixelpeeping" and I think Sebastian is right when he says, that there is no audible difference between them , and in the end, That's what counts.
Anyway here is what I did:
First I prepared a signal test with the sine wave generator in Audacity.
This is the Waveform of the testtone.
www.luzz.de/sub/audio/a10/image/FR_Ref.PNG Please use this link to open the image in full resolution.
First three tones (I forgot what frequency exactly, but according to audition they are ca. 35Hz, 3K and 14k) followed by a the range from 30Hz up to 25KHz.
This file I played in Audition with the Roland UA-M10 LineOut into the three recorders available here:
1. PCM-D100 with dedicated Line IN:
www.luzz.de/sub/audio/a10/image/FR_D100.PNGAs you see, there are some flaws, but the signal is pretty clean and linear, I come up with a closer look later.
2. PCM-M10 with dedicated Line IN:
www.luzz.de/sub/audio/a10/image/FR_M10.PNGlooks linear to!
3. PCM-A10 in LineIN Mode:
www.luzz.de/sub/audio/a10/image/FR_A10.PNGIf you look at the first Test Tone (35Hz) it has less gain than the rest of the file, about -2db. Also the overall signal is a bit "wavy" and not as linear as it is in the M10 or D100.
This looks strange but is no issue at all, for Recording, this would be easy to EQ if someone takes notice of it at all.
Now some zoomed-in images of the point where the frequency range starts.
1. PCM-D100:
www.luzz.de/sub/audio/a10/image/FR_D100_Detail.PNGSurprise, on the D100 there is not a drop in the levels, but there is some kind of "bend" in the waveform, I can't explain this, maybe someone can
. It could also be the Soundcard producing it. The "Bend" is over at about 100hz and it shows up linear from this point on. The deviation of the bend is close to nothing and it's funny to talk about. Also the D100s signal is almost clean.
2. PCM-M10:
www.luzz.de/sub/audio/a10/image/FR_M10_Detail.PNGThe M10 also has this kind of "bend", not worth mentioning. In the signal there are some unplanned frequency signals. Look at the Scale in wich level region they are, so they shouldn't bother any bats
.
3. PCM-A10:
www.luzz.de/sub/audio/a10/image/FR_A10_Detail.PNGOn the A10 you see, there is a small Level drop, It's below 40Hz, from 40Hz up it reacts just as the two other family members above.
My conclusion:
this is all theory, and it will not bother you in real-recording-life. It seems that the said frequency response in the datasheet of the A10 is actually true, and there is no cut below 40Hz but there is a small drop wich you can EQ if there is a need for. Maybe the news is, that the frequency response applies to the LineIN mode also and not only for the internal mics.
Beside this, the A10 is great to handle, small and light. This is a much bigger difference to other portable recorders, than this sound issue is. And I have to admit I might did some mistakes in this test, I am not a professional tester