Hi. In my case today I have a PC -> USB cable -> iPurifier2 -> Micro iUSB 2.0 -> gemini cable -> Micro iDAC2.Let's address this in even more thorough way, shall we?
If you want to keep your iDSD micro on all the time, you can still use the battery mode and normally not worry about the battery state. This is best if you usually use it to play music for a few hours at a time and then shut the music source off to allow the iDSD micro to top up its cells' charge. Using a USB port that is BC1.2 compliant and can deliver 1.5A of current is strongly recommended and essential if using Turbo mode.
If you want 100% availability and 24/7 operation while never worrying about the battery state or which amplifier setting is engaged, power your iDSD micro from a BC1.2 compliant USB port and make sure power is available 24/7.
If you want to have maximum play time "on the go" make sure to TURN OFF the iDSD micro when charging. If you don't need maximum playtime, make sure to TURN ON the iDSD micro when charging. and to make sure that your smartphone battery does not get drained when music stops, flash Firmware 5.2B.
iDSD micro has a fairly sophisticated charging system, but in the best Apple style, rather than festooning the device with a million gauges and LED's, we kept it as minimal as possible (we felt there where enough switches etc. as is).
If the iDSD micro is turned on BEFORE being connected to a USB source (or just a USB charger) it is in "Battery Mode" until turned off next time.
If the iDSD micro is turned on AFTER being connected to a USB source (or just a USB charger) it is in "USB Mode" until turned off next time.
Now unless Firmware 5.XB is used, the iDSD micro will actually re-charge in either mode, unless it detects a "weak power source" which is assumed to be a smart phone. Equally, in either mode the iDSD micro may draw on the battery if needed.
So it might be better to call the modes "Battery Power Priority" and "USB Power Priority".
In battery mode, if music is playing via USB or SPDIF power is drawn ONLY from the battery, the USB power connection, if present is shut off.
However, if no music is playing on any input for 3 minutes, the iDSD micro will shut down the whole analogue and amplifier circuitry to conserve power (as these draw the most). And if it has detected a "strong" (500mA or greater) charge capable source it will recharge it's battery while no music is played.
The re-charge is set to not fill the battery up to 100% capacity as this would cause cells to wear out quickly, instead charge is capped at 75%, which means battery life in this case is equal to shelf life.
Powersave mode is indicated by a blinking green LED, and if the iDSD micro is in powersave + recharge mode, it with show a blue LED.
This means as long as 'eco' mode is used and you do not play music for more than 8 hours without interruption (and your computer settings allow the iDSD micro to go to sleep and charge), the iDSD micro may be operated in battery indefinitely, if it remains connected and turned on, because it will recharge automagically whenever there is no music playback for any length of time.
In USB mode the iDSD micro will first and foremost apply USB power to keep internal systems 'alive'. If any power from the USB is "left over" after operating internals, it will be used to charge the battery.
If the power available from USB is insufficient, the iDSD micro will automatically draw the difference from the battery, which acts in effect as a booster pack.
If no music is played on any input for 15 minutes, the iDSD micro will shut down the whole analogue and amplifier circuitry to conserve power (it draws the most). Then more power is available to top up the battery.
Again, the re-charge is set to not charge the battery to 100% capacity as this would cause the cells to wear out quickly. Instead charge is capped at 75%, which means battery life in this case is equal to shelf life.
The power from a standard USB port is sufficient for operation of the iDSD micro ONLY in 'eco' mode, using a standard USB port and USB mode with normal/turbo may slowly drain the battery even in USB mode, unless the iDSD micro is allowed to enter powersave frequently enough to allow it to keep the cells topped up.
This is because the iDSD micro is USB standard compliant, so it will never draw more than 500mA, unless the USB port it is attached to includes USB standard BC1.2 signaling, in which case the iDSD micro will draw the current it needs up to a maximum of 1.5A which is enough for both 'turbo' mode operation and charging a flat battery to 80% in under 12 hours.
The iUSB nano & micro implement BC1.2 and will supply the iDSD micro with all the power it needs at a quality that rivals battery operation.
Many inexpensive USB hubs also implement BC1.2 and can supply the iDSD micro with the power needed, though the results will not be as good as the iUSB.
Further, if the iDSD micro is switched off when charging, it will fill the battery to 100% capacity. This will maximize playback time in portable use, but as the battery is now cycled past 75% it's lifespan will be shortened compared to the lower charge.
So if you do not need maximum battery charge, keep your iDSD micro on while charging to be easier on cells.
If I replace the Micro IDAC2 with the Micro iDSD (not Black Label), where should I place the iPurifier2?