Sony has taken the hand held recorder form factor and added high sample rates, 24 bit and DSD recording
This is the type of device that just couldn't have existed before the advent of solid state memory. You can think of it as a pair of very high quality microphones with a built in recorder - or as a recorder with some very high quality microphones.
Either way, you couldn't do this in the days of tape, because the motor would have been too noisy.
And that's especially true with the PCM-D100, which is capable of recording an extraordinarily high dynamic range.
The device is pretty tough. There's an aluminium body, and where plastic is used, it seems strong.
There's a big screen with a rather "traditional" looking LCD display, but when you think about it - you wouldn't want an electrically noisy computer or phone-type screen on a recorder like this where so much is opitmised for low noise. Nor would you want a complex operating system like Android that would need constant updates. You just want it all to work, even if it means that it doesn't upload to SoundCloud or play or Candy Crush Saga.
Near the top there are four useful LEDs" -12dB for each channel and the same again for "Over". Even though the metering is pretty good it's much easier to see these from a distance.
The master record level controls are dual-concentric. The outer ring controls the right channel and the inner knob handles the left. Even though I found the left channel slightly awkward to adjust because of this set up, it's definitely worth the slight hassle because one's you've balanced right and left, you can lock the positions of the controls relative to each other and adjust them both together with the bigger outer ring.
There's also a physical guard that snaps into place to avoid changing the setting accidentally.
The front panel is dominated by the large LCD screen, leaving the rest for the physical controls. It's a simple and effective layout. Pressing "REC" puts it into record-pause, and you start recording by releasing the Pause button. This could lead to missed recordings if you didn't know this in advance but I think it is a good way to do it as long as you relabel the "REC" button "Record-Ready" in your mind. What it does mean is that it's very quick to get into the mode where recording hasn't started yet but the meters are working.
There's a clear "Stop" button and, next to it, a "T-Mark" button for placing markers in the recording. To the left of these controls there's the master transport control with an up-down selector for navigating the menus. There's an additional - and rather useful - "Home" and "Back" key. Finally, above this arrangement on the left are two assignable function buttons.
The menus are clear and self-explanatory. It's pretty simple to select the recording options (PCM vs DSD, Sample rates, Limiting etc). I managed without a manual, although I don't recommend this because you might miss some interesting nuances.
On the left side is a 3.5mm jack for headphones and a headphone level control. There's also an optical digital out, as well as a jack for the remote control receiver, which is not built into the recorder.
The right hand side has a stereo 3.5mm jack for Mic in, and there's an optical input as well.
On the bottom, there's a very small loudspeaker, which is so small that it's never going to be able to do anything more than act as a sanity check - but that's OK - because this is not a boom box and if you need to do a quality check... that's what headphones are for.
The two mikes can pivot between a 90 degree angle leaning towards each other and 120 degrees away from each other. The former position is best for close-up work, and you'd use the latter for recording, say, and orchestra, when you'd need to be a lot further back.
Internal storage is very usable 32 GB and you can add to this with various types of SD card - or Sony Memory Sticks, for that matter - but who uses those?) You can set the system to "span" between internal and SD storage. It's a pretty flexible system. My preference was to record to SD cards because it's a matter of seconds to transfer them from the PCM-D100 to the slot on my Macbook Pro for editing.
This is not the cheapest device of its type by a long shot, but it's just possible that it might be the best. Let me explain what I mean by this.
The PCM-D100 is able to record very high quality audio. The recorder is capable of 192 KHz 24bit sampling, which is about as good as it gets with Linear PCM (Pulse Code Modulation - the same way that sound is stored on a CD). It's arguable that there's no point in sampling at even higher quality - at some point you'll just be recording bats. (There's a lot more to it than that, but you know what I mean!)
But that's not all.