Powering your Raspberry Pi
The Raspberry Pi and its peripherals are very critical on the voltage that is supplied to them and the micro-USB power connector is less than ideal.
Ideally, your Raspberry Pi should be supplied so that the voltage measured at the GPIO output connector or a USB port does not fall below 5.1 volts when it is at maximum load. To achieve this it is recommended that you make sure that your 5 volt power supply is set to supply 5.2 volts at load currents up to 2.5 Amps. Then run thick cabling to within a few cm of your Raspberry Pi and solder it directly to a cut-off micro-USB connector.
Consequence of Lower Voltage
Problems caused by low voltage can include a thumping noise on the EasyCap audio, slow boot-up, picture break-up and system lock-ups.
The most obvious symptom of low voltage is the lightning flash appearing at the top right of the LCD screen. Additionally, if you select the "Info" screen from Menu 2, the 4th line will tell you if there have been any low power events since boot-up. You can also run the command "vcgencmd get_throttled" at the command line. Any response other than "throttled=0x0" means that you have a problem.
Alternative Power Wiring
You can power the RPi by applying power to the 5 volt pins on the GPIO. This bypasses one stage of protection - the 2.5 Amp resettable fuse.