CORDA PCSTEP
The PCSTEP is a portable amplifier that, in addition to its analog input, also has a built-in USB-DAC. When connected to the USB-port of your PC it will strongly improve on the sound that is provided by a standard quality soundcard.
The amp has a discrete volume control (32 positions, two gain settings). This volume control is not a standard industrial solution but uses a concept in which the position of an analog potentiometer is measured using a low-power ADC and in which the output of this ADC is used to control electronic switches that set the volume level. The result is a very clean and detailed sound without any channel imbalances.
Technical details
Measures: 8.9 x 6.6 x 2.2 cm

Weight without battery: 115 gr.

Supply voltage: 6 .. (9) .. 15 Volts DC

Mean current uptake: 28 mA

Discrete volume control. Typical stepsize 1.5 dB, 31 steps.

Maximal amplification: -2 / 14 dB (low/high gain)

Input impedance: 120 / 19 kOhm

Output impedance: < 1 Ohm

The unit runs from a single 9V battery, 5V USB-power, or an external powersupply (with upto 15V). Internally the supply voltage is doubled to increase driving capacity.

External noise is removed by extensive LC-filtering of the supply voltage.

The total buffer capacity is 1700 uF to lower the effective battery impedance.

For amplification two single OPA209 opamps are used for maximal sonic performance.(No dual or quad-opamps!)

The USB-DAC is based on the PCM2702 DAC-chip by Burr-Brown.

Resolution USB: 16 bit

Sampling frequencies USB: 32, 44, 48 kHz

The 3.5 mm sockets are silver-plated.

Inside the signal path only metal-resistors and high-quality film-capacitors are used (polypropylene).

The enclosure is made entirely of aluminium.

Accessories:  2 mini-mini interconnects (goldplated)
                          USB-cable
                          tool to open the amp