Due to the change in the model range and lines of the manufacturer, Stellar Strata is currently the only integrated amplifier in the PS Audio catalog. During my acquaintance with this device, the thought constantly visited me: the “source” in this device is no less than the “amplifier”. So it turned out to be a very self-sufficient symbiosis.
PS Audio Stellar
There are many unusual things here. It would seem, well, what can surprise an amplifier with a DAC on board now? Almost everyone produces such versatile all-in-one models, but in our case, everything is a little different.
Design
Good looks – completely predictable for the Strata line. A case rounded along the horizontal edges of the front panel, an on / off button in the form of a blue logo (like PS Audio network splitters), a miniature display and a rotary volume control knob. Plus a headphone jack. At first glance, nothing out of the ordinary.
The back panel is already more interesting. One-third of it is occupied by digital inputs, another – by analog inputs (including balanced and unbalanced pre-amp output), and another third – by terminals for connecting acoustics. By the way, the terminals are very nice, massive and high quality.
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Of course, the digital part is more interesting. There is a connector for connecting to a network via twisted pair (and the device also has Wi-Fi), a USB audio input, an optical input, a pair of coaxial inputs, and most importantly, an I2S input that looks like an HDMI connector. In general, this is a rare type of switching, but PS Audio uses it extensively.
In this case, the DAC can work via I2S in tandem with its own transport, which, in turn, works with both CD and SACD disks. Of the auxiliary switching, there are control trigger connectors and a service USB port.
The DAC is built on ESS Saber Hyperstream and can handle both PCM and DSD. The input signal is not recalculated and is processed by a CPLD chip (a simplified analog of FPGA) as part of a proprietary circuit called Digital Lens, the main task of which is to reduce jitter.
The I2S input is capable of accepting PCM up to 384 kHz, as well as DSD64 and 128. Coaxial inputs work with PCM up to 192 kHz, optical up to 96 kHz, USB-PCM up to 384 kHz, and DSD64 and 128 in DoP mode.
When using the built-in streaming module, the “upper bar” will be 24/96, and Tidal, Qobuz, Spotify, Napster, iHeart Radio, and DLNA on the local network are supported by the services. You can also pay attention to the DAC output stages operating in class A, as well as the fact that passive filtering is used.
In the signal path between the DAC and the power amplifier, there is a preamplifier – and it is quite unusual. Fully balanced circuitry, assembled without capacitors in the circuit and operating in class A. In general, this is the Gain Cell circuit with a variable gain that has long been used by the manufacturer.
Next is the power amplifier. The manufacturer describes the circuit not just as class D, but as something hybrid, called “AnalogCell” and has a fairly decent declared power of 200 watts at 4 ohms per channel. If you look at the boards, it will become obvious where PS Audio’s boards are of a characteristic purple color, and where the ICEpower 200AS2 output amplifier is – the marking is visible, no one is hiding anything.
So “AnalogCell” should rather be attributed to a pre-amplifier, but it is assembled separately and on the PS Audio board. You can see that all kinds of combinations of class A with class D are options found in many manufacturers, but the implementation and sound are different for everyone.
It is also necessary to mention the manufacturer’s statement that, despite the circuitry, the device is made in such a way that the sound, by its nature, is more like a tube one. In addition to the power amplifier for working with acoustics, there is also a separate class A headphone amplifier on board – with an output power of 300 mW at 300 ohms and 3.25 watts at 16 ohms.
The case itself accounts for a very significant part of the total weight of 9.5 kg. There are no toroidal transformers or impressive radiators here – at first glance, the filling looks more like a digital source or a preamplifier. However, from a practical point of view, everything is collected neatly.
Software
The next important component for such modern digital-to-analog devices is software and compatibility. And here Stellar Strata has mixed results.
The company has several devices (DirectStream DAC, DirectStream Junior, PerfectWave DAC ) that are Roon tested and Roon ready. But Strata does not yet have such a status – and I was not surprised when the current version of Roon did not recognize the device on the network.
Rumor has it that control is possible using JRiver, Bit Perfect, Amarra, and Pure Music, but these capabilities need to be dealt with separately, I would, of course, like Roon compatibility – especially considering that the manufacturer already has positive experience.
The device’s own network capabilities are a streaming module and a native application. First, you need to make Stellar Strata friends with the network – there are not many difficulties here, but there are some peculiarities. For example, during the startup settings, the tablet connects to the device as a Wi-Fi point, and only then the application sees the device on the local network. But to tune in with such a connection is not at all easy.
If you take a wired connection – no problem. But connecting the Stellar Strata to a wireless network is somewhat more difficult. I did not succeed in registering the parameters from the application on the tablet. I had to do this from the menu on the front panel of the device – using the buttons and the volume knob, which in this case turns into a navigation knob.
Imagine how to enter a complex Wi-Fi password with such manipulations. But this is how it works. However, this is not a function that needs to be accessed daily.
The device settings menu itself, which is displayed on the front panel, is not very convenient. Not visually, not intuitively clear, and at first you need to check the instructions to understand the logic of movement. Of course, you need to go through all this only once after the device has settled in the house, but the anticipation “I’ll turn it on and listen right away” will not come true. However, this will only happen if connected via a network – the rest of the switching or operation in the USB-DAC mode did not cause any complaints.
An application for iOS devices is also a quest. It exists, but it’s not in the App Store. Didn’t work, disagreed. How do we set it? We go to the PS Audio website, rack our brains, look for where it should be, find it, read the QR code, and now the application is loaded. True, iOS does not allow it to run. You need to get to the security settings, make permission for this, and then the application will become active.
It also works specifically. Inside there is some set of settings, for the most part unusual – for example, a programmable alarm clock. However the interface is generally simple, and I limited myself to using the streaming application only for Internet radio.
Together with the fact that the upper streaming bar is 24/96 here, using the device in USB-DAC mode paired with some third-party software is much more preferable. Especially if you need to combine streaming and local file music library in one application.
As for the streaming component… I would say this – now it is more likely to be gone than it is. But let’s remember that PS Audio is a company that entered the market of devices with streaming support a very long time ago, and in its past and present there are very remarkable and well-deserved devices.
I think that in the case of Stellar Strata, in the future, everything will be decided by firmware and software updates. And of course, I would really like to see compatibility with Roon. In the meantime, we will consider the device as an integrated amplifier with a DAC on board – and, to some extent, with a streamer.
Sound
The main test took place in the variant of using an amplifier and a built-in DAC with a USB connection, but you should not forget about the possibility of connecting a familiar disk transport. And switching over I2S – unless, of course, you have something to connect in this way. But still, I wanted to focus on using it in tandem with a computer – especially since I have all the software there, an extensive music library on the server, and streaming services.
First I put on a recording of “The Best of the Dial Years” by Charlie Parker and Miles Davis. The character of the sound is detailed, with a noticeably pronounced effect of attraction, a kind of immersion in the sound. The old recording sounds rather bright and, indeed, with some vintage-tube character.
Intelligibility is not bad – and it seems that it is emphasized on purpose, due to which the sound is perceived as interesting and multi-component. The delivery is expressive – both in the middle and at the top. There is no point in judging low frequencies from this recording, so we will pay attention to them later.
With a seemingly perceived brightness, the sound is not sharp but even softened – bright, but warm. The monophonic sound also turned out to be unusual – not so much elaboration in depth (although it is present), but a very wide panorama. Of course, it’s not stereo, but the width of the sound is impressive.
The next disc is Colin Vallon Trio’s “Rruga”. There is a good rhythm and elasticity, the detail is felt higher than it really is. The presentation is not something that would be holographic, but some claims are obvious. At the same time, all this is unusually mixed with a share of warmth and softness. It turns out a slightly psychedelic atmosphere, filled with rich, but muted colors.
The velvet-air wide stage also contributes to this perception. The mid-upper range seems to be slightly emphasized, on the other hand, and the volume bass turns out to be commensurate. It seems that the whole sound as a whole, over the entire range, is somewhat emphasized and more textured than usual.
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On the whole, everything turns out emotionally, but the nature of the emotions rather goes a little into noir, into a light psychedelic, completely devoid of bravura or deliberate joyfulness. The device has an unusual character and its reading of sound. Already at this stage, it can be noted that the sound can be described in very different ways, but definitely not as boring or pedantic.
Then he put on the much-loved Diana Krall album “When I Look In Your Eyes”. And I must say, listening for 20 minutes did not send me into a deep sleep. The sound is cheerful, with savoring after tones, it seems less monotonous than usual. Emotions are perceived brighter, but no puppy joy is observed. The warmth is present, but it is unobtrusive, the vocals are well-developed and not exaggerated relative to the rest of the sound.
There is a slight touch of synthetics on the piano parts, more precisely, a light ringing color with an emphasis on semitones, but no more. And in principle, synthetics here in the sound are much less than I expected. Instead, there is warmth similar to a vintage lamp, moderate softening, and some kind of obvious “fluffiness” of the sound and volume that this sound draws. Plus a good rhythm – confident, but not impudent.
On the recording of Eddie Higgins Quartet Featuring Scott Hamilton’s “Smoke Gets In Your Eyes” you can hear the already familiar presentation of the device itself, but the style of the performance and recording of Venus Records are perfectly recognizable. In general, the amount is obtained without a bias in one direction or another – everything turned out harmoniously.
First of all, I liked the rhythm. It’s always understated, yet soft and delicate when needed—or fast and snappy when needed otherwise. The dynamics are not just good – they are emotional.
The bass is very good in terms of filling – and it is not formally simplified. The detail is the same, slightly emphasized by overtones and textures, which very well masks the fact that the most subtle shades and nuances are formalized and simplified. One kind of replaces the other, and in general the sound does not seem rustic or faded. And I didn’t expect full-fledged detail – the one I’m used to – here, but in practice this detail is much more expensive.
The presence of warmth in the sound is not annoying, although I do not like warmth. It’s just that here it is of such a quality that it is in moderation – not too much and not too little. The integrity of the picture does not fall apart – everything is in its place and well-matched proportions.
Dimmu Borgir’s album “Puritanical Euphoric Misanthropia” showed that even with such material the tract coped dynamically. But where there is a synthesizer sound on the recording, it is very noticeable, and the sound becomes a little comical, and toy-like.
And the rest – fast, assertive, provocatively, with a good scene and good detail. And very emotional, but somewhat happier than the average could be. And here it is already difficult to say how it is combined with specific music. But according to formal criteria – better than expected.
Finally, Bach’s Brandenburg Concertos. The device plays the difference between high-res and 16/44 quite clearly, the sound has a good resolution and decent dynamics.
In terms of detail, you can find several minor simplifications, there is a little bit of synthetics in timbre, but this is hardly noticeable, because the general handwriting very well masks all this, and the artificial “lamplike” clearly levels the presentation in such a way that everything as a whole is perceived quite naturally. Although with an obvious share of color. The scene turns out to be large-scale, and airy, with quite bright and drawn images, without lethargy or wadding.
Separately, I want to say a few words about the headphone amplifier. I liked how it works. The sound is neutral, detailed, and dynamic, with the slightest touch of synthetics, which, however, you stop noticing after a few minutes of listening.
Conclusion
Perhaps this is one of the very good options for devices operating in class D. The main thing is that synthetics are almost invisible, and the color looks like a lamp. Let there be warmth and softness in it, the sound is cozy, friendly, and even cute, but without cloying. It seems to be a lot but in moderation.
This is not a reference-neutral sound. But that’s exactly what he intended! And if you do not try to become attached to these criteria, then you get a very versatile device with a full-fledged digital source on board, as well as with its own bright individual sound character, unlike other equipment.
Musical Material While testing
Bach – Brandenburg Concertos 1-6 – Harnoncourt & The Vienna Concentus Musicus / HDTT1030 / DSD128 Stereo
Charlie Parker Featuring Miles Davis – The Best of the Dial Years / Nippon Crown CRCL-8848 / CD Mono
Diana Krall —When I Look In Your Eyes / Verve Records — IMPD-304 / CD Stereo
Dimmu Borgir – Puritanical Euphoric Misanthropia / Nuclear Blast 27361 65272 / CD Stereo
Eddie Higgins Quartet Featuring Scott Hamilton — Smoke Gets In Your Eyes / Venus Records VHCD-78038 / CD Stereo
Colin Vallon Trio — Rruga / ECM Records 2185 B0015433-02 / CD Stereo
PS Audio Stellar Strata Specifications
Type: an integrated amplifier with DAC and streamer
Analog Inputs: 3 RCA, 1 XLR
Analog Inputs: 1 RCA (out)
Speaker output: 2 pairs of terminals
Headphone output: 6.3mm
Control trigger input: 3.5mm, 12V
Digital inputs:
I2S: PCM up to 384 kHz, DSD64 and DSD128
Coaxial (x 2): PCM 192 kHz
Optical: PCM 96 kHz
USB: PCM up to 384 kHz, DSD64 (DoP) and DSD128 (DoP)
Ethernet: 10/100
WiFi: 2.4GHz 802.11b/g/n with UPnP support, Spotify Connect
Preamp specifications:
Gain: 12dB ±0.5dB
Sensitivity: 5.3V
Maximum output voltage: 20V
Input impedance: 47 kΩ RCA, 100 kΩ XLR
Output impedance: 100 ohm RCA
Frequency response: 20Hz – 20kHz +0/-0.25dB, 10Hz – 100kHz +0.1/-3.0dB
Signal-to-noise ratio: 1 kHz > 110 dB
Channel separation: 1 kHz > 90 dB
THD: 1 kHz < 0.025%, 20 Hz – 20 kHz < 0.05%
Headphone Amplifier Specifications:
Output power: 300 ohm – 300 mW, 16 ohm – 3.25 W
Output impedance: <4 ohm
THD: 300 ohm <0.05%, 16 ohm <0.06%
Power Amplifier Specifications:
Gain: 30.5 dB
Output power: 8 ohm, 1 kHz, 1% 120 W, 4 ohm, 1 kHz, 1% 150 W
Frequency Response: ±1dB 20Hz-20kHz, -3dB 7Hz-40kHz
THD: 1 kHz, 10 W/4 ohm 0.02%
Channel separation: 1 kHz > 90 dB
Power consumption: 50W (average), 600W maximum
Dimensions (WxHxD): 430x332x82.55 mm