Pro-Ject Stereo Box DS3 Integrated Amplifier

Pro-Ject Stereo Box DS3 integrated amplifier is a compact design with useful features. There is a built in MM or MC phono stage as well as three line level inputs and built in HD Bluetooth to stream music, podcasts and audio books from your smartphone or any other bluetooth device. 

This model features a powerful 150 watts per channel amplifier, housed in a beautiful solid aluminium case. The DS3 is available in classic silver or black. There is also a trigger input that can automatically turn on other suitably equipped devices.

Good connectivity

The DS3 features a 6.3mm headphone socket on the front of the case as well as 4mm banana plug terminals for the speakers. Moreover, there is a variable RCA output, that makes it easier to connect a subwoofer (the variable output will track with the volume control so that the subwoofer volume stays in sync) There are also three analogue inputs.

Analogue volume control

The volume control is motor driven. This is used instead of reducing the audio quality, by sending it through an electronic volume control. A remote control is supplied that will also switch the inputs.

Case design

The Stereo box DS3 is designed and handmade in Europe. The small form factor saves materials and is only as big as necessary. The classic design is built using the best materials including a rigid aluminium case and the best audio grade components.

Efficient class D amplifier

Due to it’s compact size and high output power the DS3 uses a dual mono, class D amplifier. Unlike linear amplifiers, Class D amplifiers are up to 90% efficient and generate much less heat. Linear amplifiers are usually built using bipolar transistors, in a Class B or Class A/B configuration, this means that they always have a small bias current flowing. On the other hand Class D amplifiers use MOSFET transistors, that can switch at a high frequency. That is because, with Class D, the audio signal is modulated onto a high frequency carrier. This is filtered out at the output, to recover the audio signal.

Moving magnet and moving coil phono cartridges

There are two main types of phono cartridges available - moving magnet (MM) and moving coil (MC). The DS3 has a switchable input so that either can be used. This is needed because the output voltage for moving coil cartridges is much lower than moving magnet cartridges. Sometimes just fractions of a millivolt. 

The DS3 MC input has an impedance of 100 R and a gain of 60dB, while the moving magnet input has an input impedance of 47K with a gain of 40dB. These values have to be correct to get the most out of the cartridge.

Bluetooth codecs

Finally, The DS3 also has HD Bluetooth capability. Bluetooth is not known for great audio quality, however, now there is aptX HD. This is a Bluetooth format that can send high quality 24-bit files. It also features a better signal-to-noise ratio, reducing distortion. The original aptX and aptX HD both use 4-1 compression however the original has a “CD like” 16-bit / 44.1 kHz signal, with a bit rate of 352kbs. While the HD version has a 24-bit / 38kHz signal and a bitrate of 576kbs.

About Pro-Ject

Pro-ject was founded in 1991 when CD was king. However, their focus from the beginning has been to provide the best analogue experience at an affordable price. The Pro-Ject 1 was the first turntable and it rapidly became a classic. Today Pro-ject sell to more than 80 countries. All the turntables are built from scratch, using cutting edge technologies. Moreover, they also make amplifiers with a leaning towards vinyl.