Review: Sony CAS-1


Mis à jour le 26 February 2019.

Sony CAS-1
A Type-A port for a USB flash drive is located above the headphones output

This week we’re testing the Sony CAS-1 Compact Audio System, made for listening in smaller rooms and compatible with digital music up to 24 bits/192 kHz and DSD, via its USB and Bluetooth Hi-Res Audio (LDAC) inputs. The Sony CAS-1 is designed to be used via the USB port of a computer in order to convert and amplify all types of music. A USB flash drive can be connected to the second USB port to read audio files. Any smartphone, tablet or Bluetooth laptop can stream music wirelessly to this amp. The contactless NFC external devices are also supported.

Sony CAS-1

The Sony CAS-1 audio system amplifier adopts a vertical format to take up less room on a worktop for example. It adapts well to an office desk alongside a computer. Its cover plate measures only 5.5 by 21 cm approximately. The cabinet is finished with high quality plastic for an easy grasp. The front panel features a Type-A USB port (for USB flash drives), a 3.5 mm format headphone output and a source selector (USB A, USB B and Bluetooth).

Sony CAS-1
The Type-B USB port can be found at the bottom of the back panel

The back panel features screw terminals (banana plug compatible), the USB B input as well as a Bluetooth pairing button and gain selector. There is also an air vent at the top of the cabinet which hides a heat sink.

Sony CAS-1

The bookshelf speakers in the Sony CAS-1 Compact Audio System are 2-way bass-reflex models. The 2.5″ diameter midrange/bass driver features a carbon-fibre cone whereas the tweeter is a coated fabric dome, measuring half an inch in diameter. The resonator (circular port) is underneath the speaker, which is mounted on rubber-tipped brass decoupling spikes. Two pairs of high spikes are supplied to direct the speaker upwards for listening in smaller spaces.

Sony CAS-1

Sony supplies a small credit card-sized remote control, a USB A-B cable, and tin-plated copper speaker cables. Two speaker bases are also supplied for better stability and improved air circulation from the down-firing port (if, for example, the speaker is placed on top of thick fabric).

The overall finish of the two speakers is excellent. Everything has been carefully designed.

Sony CAS-1

Sony CAS-1

Test conditions

We listened to the Sony CAS-1 Compact Audio System with a Bluetooth smartphone as well as a Raspberry Pi2 computer using the Linux Volumio distribution, which enables a bitperfect digital audio output via USB. As well as the amplifier’s speakers, we tested its headphone output using a Texas Instruments TPA 6120A2 headphone amp paired with the same brand’s DAC (Burr Brown PCM1795 – 24/192 and DSD compatible). We listened to FLAC and DSD format files. It’s worth noting that the DSD64 supported via the USB-B input operated natively even though Sony recommends a DoP setting (DSD over PCM).

Sony CAS-1

Listening impressions

With the speakers: don’t be deceived by the size of these little 2-way bookshelf speakers and think that they can’t produce a balanced sound. In theory, they aren’t high-performing in bass but in practice, Sony has (clearly) used progressive loudness. At very low volumes, bass is immediately present for delivering a balanced sound from bass to treble but these bass levels are lowered the more you boost the volume. Once you go past the halfway stage, the progressive loudness is deactivated to not cause too important an excursion for the 2.5″ bass driver cones, which could damage them. Paired up with other speakers (Q Acoustics 3050 for example), the little S-Master HX amp is heavy in bass, which justifies the presence of the active equalizer.

Back to the CAS-1 speakers whose delivery is highly accurate. Particular attention has been paid to the sound directivity of drivers and these can be listened to without necessarily directing them towards listeners’ ears at a distance of 30 cm. Bass is well present, medium is very detailed (which is normal for such a small driver) and treble is extremely clear even in SBC Bluetooth (DSEE HX oversampling is no stranger to this). The little tweeter is a real joy as it distills a clear sound and features well structured sound stages. This is the highlight of the Sony CAS-1 and as its speakers are so small, the sound can be adjusted by spacing them out or directing them.

Sony CAS-1

Jazz, classical, rock, live music, everything sounds good.

Used with headphones, the sound signature is very different. This was to be expected as Sony amplification hasn’t been fully developed for headphones. The Texas Instruments amp paired with the Texas Instruments DAC delivers a consistent sound without excess but with very good dynamics. The only fault we could find was the short extension in the bass range. The strength of the speaker amplification is the weakness of the headphone amp. The Sony PHA-1 headphone amp is more generous in terms of low frequencies (but it is less powerful). The balance is indisputable and the delivery is never too heavy. Stereo is very striking and the sound stage is wider rather than deep. This headphone output offers both meticulous and dynamic sound. The gain adjustment and power reserve should cope with demanding headphones.


The Sony CAS-1 Compact Audio System is in line with requirements regarding quality listening in small spaces with a computer or Bluetooth source. The speakers are excellent ? very good drivers and wide directivity, as is the amp. We liked the detailed and generous delivery of low frequencies, from the lowest volume of the speakers. The headphone output is also very good and will delight lovers of big thundering bass.


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