So there I was: I had a beautifully-built fully-balanced streaming DAC, and a beautifully-built fully-balanced power amplifier … and a single-ended (ie. with RCA plugs) preamplifier between them. I’d been dissatisfied with that pre-amp for a while, principally because it’s maximum gain was … 1.0. That is, the output level was equivalent to the input level, minus any attenuation applied by the volume control. As an old-school hifi guy, I’m uncomfortable when a volume control is rotated to somewhere near the maximum. Which is where this pre-amp’s volume control spent most of its time.
The Schiit Audio Freya S balanced preamplifier solved both those problems. It has two fully balanced inputs (and three single-ended) and both fully balanced and single ended outputs. And in one of its modes, its gain is 4.0, or 12dB. I could have the volume control at around 12 o’clock for entirely satisfying levels, rather than at a near-end-of-range 3:30 or 4.
Which is why I bought it. Now I’ve been using it for a few weeks, allow me to pass on what I’ve learned. That learning includes some tests which suggest the best mode in which to use it the Freya S.
- The Schiit Audio Freya S is a fully balanced preamplifier
- Made in California (and perhaps Texas)
- Two balanced inputs via XLR, three single-ended inputs via RCA
- One balanced output via XLR, two single-ended outputs via RCA
- Selectable output mode: passive with maximum gain of 1 (ie. attenuation only), active with maximum gain of 1 and active with maximum gain of 4 (12dB)
- 128-step relay-switched volume control for low distortion, crosstalk and channel mismatch; 0.625dB per step
- Aluminium remote control included
- THD via active stages less than 0.002%
- IMD via active stages less than 0.002%
- Crosstalk better than 85dB across the audio bandwidth
- Signal to noise ratio via active stages better than -110dBA
- Output impedance via active stages: 75 ohms single-ended and 600 ohms balanced
- Dimensions: 407mm wide by 224mm deep by 51mm tall
- Weight: 5kg
- The Schiit Audio Freya S is a ridiculously good pre-amplifier at a ridiculously affordable price. By all conventional assumptions, it was out of place in the review system, but it performed superbly. For best performance, choose the active X1 mode.
- Price: $1100
- Available at fine high fidelity retail outlets, and direct from distributor's retail division here
More about the Schiit Audio Freya S balanced preamplifier
I should first note that I agonised for a while between the Freya S and the Freya+. The latter is definitely the cooler option, with its four 6SN7 valves poking out the top, while the Freya S is solid state (now we know to what the “S” refers). As such, it is specified to slightly higher standards, and it’s way less expensive. With long-term use in mind – valves do expire sooner than transistors – I opted for the S.
The front panel has three control buttons and a volume knob. None of the buttons is for power or standby. There’s a hard-wired power switch on the back, but otherwise it simply remains on all the time. It takes thirty seconds to become operational when you switch on power – I have no idea why – so there’s a strong incentive just to leave it on.
What the three buttons do is mute the output, select from between the five inputs and choose the output mode. There are three output modes. One is a purely passive mode: the input is passed to the output via the volume control, but neither amplified nor even run through any active electronics. Another employs the electronics – this allows better control of things like input impedance – but runs at a gain of 1.0 (ie. 0dB boost). Schiit Audio calls these electronics its Nexus stage. The third choice gives the aforementioned (up to) 12dB gain.
I kind of skipped over the volume control, but let’s talk about that. The device behind the knob is not an analogue potentiometer through which the signal is running. It is a controller for a relay-switched stepped attenuator, essentially a resistor ladder, on the circuit board. Each step is 0.625dB, or 5dB per 8 steps. There are 128 steps for a full range of 80dB. (If you can still hear a whisper at minimum volume, just hit the mute button.) There is a clicking of relays as you adjust the volume. I don’t have a problem with that. Do you?
There are also nine LEDs on the front panels to show you the state of play.
I simply have to highlight the remote control. It is a little thing with keys that match the functions provided on the front panel. Ho hum. Except that it comes with a solid aluminium body. That’s impressive.
But not unprecedented. What must surely be unprecedented is that you can buy a replacement or spare for the insanely low sum of just $39!
Finally, a note about names. Schiit Audio names its products after figures in Norse mythology. Freya – or, more correctly, Freyja – is the Norse “goddess associated with love, beauty, fertility, sex, war, gold” and some kind of prophecy.
Using the Schiit Audio Freya S
I’ve been using the Freya S for a couple of weeks now, and it seems to me to be entirely transparent. My other equipment would seem, on paper and pricing, to outclass this preamplifier, but it doesn’t. Here’s what I’ve been using it with:
- Avid HIFI Ingenium Plug&Play turntable with standard cartridge (review here) and with Grado Timbre Series Opus3 cartridge (review here), or Rega Planar 3 turntable with Goldring 1042 cartridge (RP3 review here), via Moon 110LP V2 phono preamplifier
- Moon 280D Streaming DAC
- Moon 330A power amplifier
- Dynaudio Contour 20i loudspeakers.
Had there been any performance weaknesses, this equipment would surely have revealed it. They revealed nothing but pure music.
Nor were there any operational weaknesses. Well, if you’re inclined to switch off your preamplifier, then you’ll have to wait thirty seconds after switching it back on before you can experience any music. And the clicking of the relays as the volume is adjusted are very apparent. They don’t worry me at all, but I can imagine some find them off-putting.
Also, it took me a little while to work out which keys on the front panel and on the remote did what. That’s because the markings were small icons, which I always find hard to interpret. But, as I did, you’ll learn what does what in fairly short order.
Finally, in all the photos in this review you will see a prominent red marking on the volume control. That’s not original. It’s my mod. The volume level indicator is a small dot on the volume control which was invisible to me from much more than a metre away. Even though it’s controlling a separate circuit, the volume control isn’t infinitely spinnable. It operates across the same physical range as a potentiometer-based volume control. When you use the remote control, a motor turns the volume knob, which in turn clicks the relays over to a new set of inline resistances. So the position of the volume knob shows you what the level is … if you can see it. A small strip scissored from a roll of red-colour electrical tape allows me to see it. All the photos show my very slightly modded Freya S.
Measuring the Schiit Audio Freya S
I know, I know. It’s all about the sound, not the measurements. Fact is, poor measurements may result in audible effects. That said, I am fairly confident that no one can hear the difference between, say, 0.01% THD and 0.001% THD. No, I’ll go further. I’m extremely confident. Still, like so many things in high fidelity, measurements are a reasonable proxy for quality. If a company won’t optimise the measurable things, what makes you think it will somehow make it “sound better”?
Fortunately, I can check some of these things. And some of the measurements proved to be quite instructive. And others changed my mind about the optimum output settings.
With the Freya S there are both output options and connection options. Since I’m using balanced connections, my measurements were all based on that: balanced in and balanced out. For the source, I used my Simaudio Moon 280D streaming DAC. I first measured the 280D anew with a 24-bit, 192kHz PCM signal, and then with its output delivered via the Freya S.
Would the Freya S add distortion and noise? Perhaps limit its frequency response?
Well, duh, of course it would do all of those things! No pre-amplifier has yet been invented that wouldn’t. The important question is: how much?
So, let’s first look at noise performance. After my listening, I settled on a volume output setting of the knob pointing at 1 o’clock for an enjoyably high level of sound with the Nexus X4 output selected and 3 o’clock with Nexus X1. I chose 3 o’clock for passive, even though it was significantly quieter than 3 o’clock in Nexus X1 mode.
Wait … what? Aren’t Nexus X1 and passive supposed to be the same gain? Yes, well they are when you’re using single ended connections (I checked), but with balanced connections the Nexus X1 output level is 6dB higher than the passive connections (give or take, it seemed to vary by up to a decibel depending on where on the volume scale the knob was placed).
We’ll see why notwithstanding this I chose 3 o’clock when we get to distortion measurements.
The noise level from the Simaudio Moon 280D was -115.6dBA. Via the Freya S in passive mode (with the volume control set to 3 o’clock) it was -110.9dBA, with the Nexus X1 stage engaged it was -111.7dBA, and with the Nexus X4 stage employed and a volume setting of 1 o’clock, it was -100.1dBA. That was a surprise to me. I hadn’t heard any difference but picking between noise levels of -100dB and -110dB is probably impossible in the real world.
That said, all else being the same I’d choose the lower noise level. You never know if some weakness in performance might sneak up and reveal itself in a particular piece of music. The noise levels also slightly favoured the Nexus X1 mode over passive, but was less than a decibel. I wouldn’t both even considering that.
Here’s a graph showing where the noise occurs in the frequency spectrum (not quite sure what that weird notch up around 40kHz is, but I’m absolutely certain that it’s inaudible):
It looks like the higher X4 noise floor is just built into the greater gain.
Now, here’s a table showing the single-figure results of a whole series of tests. Max means that the volume control was set to the maximum. 1pm, 3pm and 4pm were my best estimates of setting the level according to a clock dial. That weird +24dBu one at the extreme right is explained below.
Now, let’s look at the distortion figures. Out of the Moon 280D we have insanely, absolutely miniscule distortion levels for both THD and IMD. They’re 0.00018% for THD and 0.00065% for intermodulation distortion. Obviously, all the figures for both after running through the Freya S are somewhat higher. You can check them out in that table, but you’ll see that in most cases the THD and IMD are both still less than 0.003%, figures unimaginably low a few decades ago. But I did say “most”. I was startled to find that in passive output mode, when the volume control was advanced to the maximum the THD and IMD were both around one third of one percent – ie. more than 0.3%. That remained the case even when the volume was backed off to 4 o’clock. But at 3 o’clock in passive mode THD and IMD had both virtually disappeared, to less than 0.00095% in both cases.
With the same setting of the volume control knob – 3 o’clock – the distortion in the Nexus X1 mode was very slightly better (as was the noise). And I could turn the volume up to maximum in that mode while still retaining impressively low distortion numbers of less than 0.002% for both THD and IMD.
I guess that’s not surprising. The active Nexus circuitry effectively isolates the source device from the output device (in this case, my analogue to digital converter). The passive setting connects them directly, apart from some passive resistance between the two. That can result in somewhat unpredictable interactions and incompatibilities. Apparently all is fine with regard to distortion to a certain level on the volume control. But beyond that it goes poorly.
However, when I measured the frequency response in various states, the result was kind of reversed in the passive output mode. Here’s a graph showing the frequency response at three setting levels compared to the source with the Freya S in passive mode:
As you can see, the low-distortion setting of 3 o’clock results in a measurably inferior (although, I suspect, still inaudibly different) frequency response, as does the high-distortion 4 o’clock setting. The maximum 5 o’clock setting produces a high frequency extension very little reduced compared to the source. Passive pre-amps are very much subject to the whims of the equipment into which they’re plugged.
Now, let’s look at the frequency response in different way: we’ll compare the passive, Nexus X1 and Nexus X4 settings at roughly comparable volume levels. In this case, I used the software to subtract the Moon 280D’s response from the measured response, revealing something roughly representative of the Freya S preamplifier’s actual response:
I had the volume control set at high-ish but realistic volume level. Clearly, passive is the weaker setting. (Ignore the uptick at the extreme right – the software isn’t perfect in its comparisons). But the passive that I’m rejecting here still manages to be just 0.6dB down at 20kHz. (The other two are in excess of 40kHz before reaching -0.6dB, and hit -1dB at around 60kHz.)
I note that Schiit Audio claims a crosstalk of better than 85dB. On my measurements, I got better than 95dB, and for the X1 output mode, better than 105dB. That’s the one I’ll be using.
Oh, one final thing I should note: for the purposes of measurement, I could not turn the Freya S up to full volume in Nexus X4 mode. That was because it exceeded the maximum input value of my ADC. The ADC can support input levels of up to 24dBu, which in non-pro terminology is just under 12.3 volts RMS. Even though for reasons of purity – excessive devotion to excellent numerical measurements perhaps? – I have decided to stick with X1 for listening, it’s worth remembering that the Freya S can pump out more than enough voltage than any equipment will required, and even at this extreme its THD and IMD were only around 0.0025% each.
I’d bought the Freya S in part because of the 12dB extra gain, but it seems to me that the Nexus X1 output setting provides the best performance, with significantly less distortion and noise than the Nexus X4. And you don’t have to worry with X1 about advancing the volume level high enough to push the distortion into 0.3% range, which can easily happen in passive mode. So Nexus X1 it is for me from here on, despite my mild discomfort with a volume knob pushed a long way towards the max.
A recommendation? If you’re after a preamplifier with full balanced support, and don’t have more than ten thousand dollars available for the purchase, the Schiit Audio Freya S, or perhaps the Freya+ if tubes are your preference, is clearly the go-to preamplifier! I’m very satisfied by the choice I made.