Chord Hugo M Scaler
Headfonics 2020

Chord Electronics Hugo M Scaler Review

Performance Impressions

What to look for?

Normally, I would say sound impressions but here I think performance is more adept at describing how the Hugo M Scaler performs.

The enhancements fundamentally lie in the technical domain but that is not to say timbre is not unaffected.  Rather, this is unlike a PMEQ or EQ effect, it is not a bludgeoning tool to completely change the tuning bias of any particular source or amp output.

Your system’s level of dynamic range and how well you know it, combined with just how resolving and adept your headphone is will play a key role in appreciating what the M Scaler can do. I generally found the better the system the easier it was to hear how dramatic some of the changes were with the M Scaler inserted into the chain.

What will you possibly hear? I have to say two things stuck out for me when moving from the by-passed 44.1k red OP sample rate setting to the 784kHz white setting which has been the most dramatic difference when paired with the Qutest.

Dynamic Range “Vivid”

The first is just how precise everything sounds without actually sounding digitized. The red or 44.1K keep rates where they are for most of my music’s native sample rates. The general presentation sounds great at that level with the Qutest but with the M Scaler, everything sounded much more vivid.

You suddenly become far more aware of little nuanced details with imaging cues right on the edge of the stereo field that has a lot more ‘pop’ to them. It almost made the Qutest sound a little vague without the M Scaler which honestly is not fair at all on the Qutest because it is an awesome DAC but there you are.


A good example of this was Hifiman’s Jade amp paired with a Stax 007 MKII. For this we used a 24BIT/96k FLAC recording of Beth Ditto’s title track from her 2017 Fake Sugar album, pushing the marker in the song to around 65-68 seconds.

This is where the mix opens up from a sparse solo lead vocal focus to include the majority of the instrumentation – strings, percussion, etc. You also have a new mix of Beth’s solo vocal to produce a more harmonized layering.

Bypass Sound

With the M Scaler setup for USB from the PC Source and working ASIO Chord 1.05 via Foobar2000 to a dual BNC connected Chord Qutest, we set the first few runs with the red 44.1k or bypass setting. Here the sound was as you would expect from a pure Qutest setting.

This was a very smooth and detailed presentation, particularly on the vocals. The timbre was also quite natural and instrumental separation was accurate. The Stax 007 MKII has a slightly mid-bass to lower-mids bias unlike the cleaner Hifiman Jade headphone so for my money the interpretation was spot on.

Upsampled Sound

However, once we upsampled to the maximum rate of PCM 768kHz (from 96kHz input) the track took on a very different dimension. The first thing noticeable was the amount of perceived detail from the mids upwards.

You get a strong perception of more headroom, an airier soundstage with more resolution in the upper mids. The Stax 007 MKII treble sounded like it had a shade more presence which in turn delivered a slightly cleaner timbre than the red bypass rate.

I would also argue that the transient response or timing and pace of this pairing sounded more convincing. Guitar plucks hit and faded in a tighter manner than the softer bypass red performance.

Second, vocal presence is much more electrifying whereas the red bypass sound is a little faded and lacking in impact. Hence, the term “vivid” is apt. Vocals are clearer for me delivering a lot more micro-detail with the upsampled maximum rate. You can hear the additional definition in the texture, subtle breath intakes and mix voice intonations are much easier to pick out.

Also, there is this underlying synthy-type beat just below the vocal that has a presence within the first minute of the track. I would say it is around the mid-bass to the lower-mids max. I have no problem picking it out at the red level but it suddenly became more defined and lively when moving to the top upsampling rate via the M Scaler.

That liveliness and enhanced dynamic range drives the track a bit better, offers more PRaT in general that makes the track seem pacier and more engaging.


The second observation is indeed the timbre and I have alluded to that in my description above. With the red by-pass linked to a Qutest-electrostatic amplifier pairing, I felt the low-end of my system take on a touch more body and warmth but also sounded softer in comparison to the White 784kHz upsampling setting.

The 784kHz upsampling setting via the M scaler sounded more reference-like on the same setup but had a much more pleasing tone to the mids and treble. Not a dramatic timbral change but much more refined in its delivery with more detail in note texture and body.

From my Qutest/Jade/Stax setup testing, I felt that reference sound was coming from not only a livelier treble presence but also a subtle reduction in potential bass bloom.

With the bypass on, the Stax pairing felt a little more even-harmonic biased. Upper harmonics were not being pulled on as much by the majority of instruments that need it to sound crisp and clear. Percussion and vocals, in particular, were the softest and warmest offering the most note decay and the least separation.


A-Ha’s “To let You Win” from their 2000 Minor Earth Major Sky album is a nice example to explain how the timbral changes came into play.

Note, this is a 44.1k/16BIT FLAC track served from Foobar2000 via ASIO Chord 1.05/USB to the M Scaler and then dual-BNC out to the Chord Qutest. From there it is a Kingsound M20 tube amplifier combined with the Stax 007 MKII. The supplied YouTube recording above is a lower rate and may not convey as much information.

From 30 seconds to 55 seconds into the track there is a kick drum underpinning the basic timing of the song. From approximately the 55th second the song sort of expands with an accompanying bass guitar and the lead percussion.

Together, they give the song some depth, warmth, and weight to drive the song forward in terms of PRaT. It also ensures the timbre of the instruments are inviting rather than clinical to match the tone of the lead male vocal.

Switching Samples

Now with the M Scaler sample on red or 44.1k, we are bypassing the upsampling capability and working a regular signal via the Qutest to the amp. With this signal, the bass has a comparatively enhanced level of bloom and sounds plentiful but not as defined as switching to the maximum 784kHz rate.

Once we switch to the 785kHz rate the bass tightens up and pulls back from bloom and instead sounds punchier with better low-end layering. That higher upsampling rate tighter low-end drains a little of the initial excessive warmth out of the resulting timbre I hear from the Stax setup.

As a result, instrumental and vocal notes from the midrange upwards sound more balanced, slightly more neutral, and cleaner.

Chord M Scaler

Headphone Synergy

Not every headphone is optimal with the Hugo M Scaler and that’s an important point. In my opening statement in this review, I spoke about the use of a Hifiman HE5SE at CanJam Singapore in 2019 to do some quick testing.

Quite apart from it being an open headphone design in a noisy trade show environment it images quite poorly and not the most efficient of headphones either. I honestly struggled with the synergy of these headphones and went home hoping I had not made a mistake in electing to review the M Scaler.

Best setups

Roll on 12 months and via trial and error, the choices are that much easier to state in terms of good synergy for headphone users.

Given the technical prowess and subtle changes in the timbre, good-quality electrostatic systems seem to benefit the most. If you do decide to go planar or dynamic headphones then the likes of Stax’s 007 MK II (009 may even be better), Sennheiser’s HD800, Abyss’s Diana Phi, or Hifiman’s Susvara combined with a highly resolving analog amplifier will qualify.

What’s the common thread running through those 4 choices? Technical capability in terms of speed, level of detail, and sound staging prowess. A headphone that is known for imaging, micro-detail retrieval, and a 3-dimensional type of staging performance is going to gel with the M Scaler behind it.


As an example of one of the headphones we mentioned under synergy, we connected the Diana Phi to a Violectric V281/Qutest/Dual-BNC/M Scaler chain with a USB input from the PC/Foobar setup. Here we ran another FLAC A-ha track from the same 16BIT/441.k album called “The Company Man”.

The Diana Phi proves that much of what we described in the M Scaler’s performance is not just reserved for electrostatic headphone systems. The Phi is a neutral and clean flagship headphone with incredible speed and detail. Perhaps one of the best I have tested to date outside of the Susvara.

Bypass Sampling

With the red bypass low rate, the Phi sounded natural to neutral with a similar level of low-end bloom and a comparatively faded vocal and treble presence.

The information was there but had a slower pace of delivery, perhaps slightly longer levels of decay and separation, and not as spectacular as we knew it could be. Technically, this level was pleasing on the timbral level but a bit soft with less dynamic range.

Maximum Upsampling

Once we clicked on the maximum sampling rate the Diana Phi started spitting out reference-quality perfection. The low-end bloom died down and definitely there was a lot more perceptible information being conveyed from the mids and beyond. That familiar ‘vivid’ sound I got from the Stax pairing was very easy to pick up.

One notable aspect of the Diana Phi pairing was the level of detail in the lower-mids instrumental texture. Bass guitar plucks with similarly timed acoustic guitar strumming, creating a single harmonized note in the mix, sounded very detailed with the M Scaler on maximum upsampling.

You could make out the depth in the note and the two individual instruments’ own unique timbre. With the upsampling turned off (red) that separation was not as clear. You get more of a perception of warmth behind the acoustic guitar plucks rather than an individual bass guitar pluck.

Select Comparisons

NuPrime CDP9



The CD9 is more of a high-end swiss army knife for audio duties than a dedicated upsampler like the Hugo M Scalers. It is a DAC, CD player as well as an upsampler but it does come at a much lower price of just under $2000.

Like the Chord M Scaler, the CD9 has a switchable upsampling capability with a number of preset levels that can lift a signal from a wide range of sources. That includes CD playback, optical, coaxial, and USB but not BNC. Sampling rates are as wide as the M Scaler ranging between PCM and DSD, from 44.1kHz to 768kHz or DSD64 to DSD512.

Because it is also a DAC the CDP9 also offers analog outputs both balanced and unbalanced and even a small 3.5mm TRS output stage for headphones and earphones. The M Scaler requires a secondary DAC component to complete the signal chain and preferably one with dual-BNC input.

Unlike the Chord M-Scaler, the CDP9 uses an off-the-shelf delta-sigma ES9028PRO DAC chipset with a switchable power supply. The demands for upsampling are also via FPGA like the M Scaler but this is also mixed in with power requirements for second stage decoding into an analog signal as well as reading CDs. T

he M Scaler has no such power demands other than its FPGA-driven upsampling so noise is less of a factor.

NuPrime CDP-9


The setup for this comparison is as follows. 44.1K/16BIT into Foobar2000, Windows 10 with WASAPI for the Nuprime CDP9 and ASIO 1.05 for Chord.

From the PC it is USB to both DACs then dual-BNC to the Qutest from the M Scaler and dual RCA to Hifiman’s Jade amplifier. From the NuPrime it is also dual analog to the Hifiman Jade amplifier. Headphones used include the Stax Sr007 MKII and the Abyss Diana Phi.

Stock Sound

First is the stock sound. The M-Scaler/Qutest pairing is much more dynamic sounding, with a fuller and slightly warmer instrumental timbre and a more holographic soundstage.

You hear it most on the low-end where the Chord setup sounds deeper but also has a tiny bit more bloom and less mid-bass punch. The CDP9 sounds cleaner, punchier but a little drier on notes beyond.

The CDP9 has been tuned to be a little more expressive and energetic from the mids upwards. Treble has a stronger presence, more typical of classic Sabre DAC clear but slightly hard-edged signatures and not as wet as the Qutest.

The Qutest is lively up top, more so than the Hugo 2, but not as glassy or dry in its overtones as the CDP9. You get less of that odd-harmonic filtering down into the timbre with the Qutest. Combine that with slightly more bass bloom and more depth and you get a smoother full-bodied natural sound.

NuPrime CDP-9


This is a strange bit for me with the CDP9 upsampling as compared to its stock sound. I am not entirely sure the PCM44.1k base rate is purely a bypass filter on the CDP9 like the red 44.1k rate on the M Scaler. The reason for that is the subtle tuning changes when I switch between non-sampled and sampled 44.1k on the CDP9.

First, I do detect a very slight diminution of dynamic range but this could also be a dB setting because it is a lot lower on the DSD sampling alternative on the CDP9. The second is the low-end of the 44.1K sounds slightly diminished and more linear in its tuning compared to when sampling is turned off.

Now, to me, the upsampling on the CDP9 from there up to 768kHz sounds like it is increasing the resolution on that 44.1k tuning and not the stock sound. That means it stays relatively linear but like the M Scaler, you definitely do get an enhanced level of perceived detail in the mids upwards.

Staging expands out a little above your head and there is what I call a bit more “fill” in terms of imaging in the upper mids and treble.


That is not too far from what the M Scaler does but there are a few differences. The first is the level of perceived digitization in the upsampled sound quality.

Beyond the 96k sampling rate, the CDP9 starts to sound slightly artificial to my ear compared to the M Scaler upsampling. 96k is the perfect level for the CDP9 in terms of balancing enhanced perceived resolution and a natural sound to its core signature.

The second difference is how the Chord Hugo M Scaler/Qutest pairing keeps everything sounds natural regardless of rate. You do get a more reference sound but it’s more beneficial than artificial.

The M Scaler shapes to reduce the bass bloom and enhance the vividness of the upper mids and treble clarity. It does not sound digital at all. It sounds, even more, real than its 44.1K relaxed presentation so I tend to keep it on 768K sampling for everything.

You could argue the third difference is the additional DSD upsampling on the CDP9 which the M Scaler does not have. I can see why, and I alluded to that in my original CDP9 review. It is too soft, dB takes a hit and vocals are not to the fore. PCM on the CDP9 is better but both are not as natural and vivid as the M Scaler treatment.


Sofware-Based Upsampling


$119 a year or $499 one time life payment

The arguments

Roon has often argued that techniques such as upsampling are better applied closer to the source file in the system setup and that a PC has a more powerful CPU than many DAC’s out there for FPGA computations.

For many commercial DAC’s that may well be true. However, whilst the M Scaler still may have to receive a signal from the PC it can argue that it is about as close as it can get without jumping into the PC. Second, the source does not even need to be a PC and here PC CPU power becomes moot if it is a regular CD Player, for example.

Finally, the M Scaler’s dedicated FPGA setup and processor will likely be a lot more isolated for jitter and noise than PCs unless you switch Roon’s Clock Master priority setting to 1 and they may lead to instability on your PC if you are heavily multitasking.

I actually tried Clock level 1 and for the most part, it was fine on a hefty AMD Ryzen 20GB RAM setup. However, the odd time I get some disruption that I didn’t get at the default, (setting).

Chord M Scaler Roon


Roon actually comes loaded with some pretty extensive sampling and filtering techniques in its DSP engine. Quite apart from sampling from 44.1k up to 768k, you can also adapt your filtering technique from linear to minimum phases depending on your preferences.

The Chord Hugo M Scaler does not use filtering typical of what you find within GUI-based OS layering for delta-sigma DAC implementations. Neither does it possess the ability to choose the max level of bit sampling alongside the sample rate such as 16BIT to 32BIT.

Having said that I tend to set that anyway inside Foobar2000 when transmitting via ASIO to the M Scaler so it is already there in my non-Roon media setup.


The treatment of the sample with the Chord Hugo M Scaler set to bypass and upsampled via Roon only actually follows a similar pattern as the M Scaler’s upsampling in terms of improvements in the technical domain.

However, the qualitative gap between the 44.1k sample rate and the 768k does not seem quite as substantial as the M Scaler. I can indeed pick up a slightly better vocal performance and the generally more vivid midrange/treble via Roon but it is not as dramatic. Instrumental separation does improve. The decay on 768k Roon upsampling seems slightly shorter which helps with the bass layering for me on some of my punchy synth-wave tracks.

The M Scaler, by comparison, has upsampling adjustments at 768k that are so much easier to pick out with the setup used. Bypassing sounds lifeless at this point with far greater detail and dynamism at the max rate.

Roon does a good job with injecting a more instrumental separation and air but the technical change-up is not so immediate and lacks the same “vivid” factor of the M Scaler’s similar rate.

Chord M Scaler

Our Verdict

The Chord Hugo M Scaler is possibly one of the most intriguing journeys I have had in a long time when writing a review. I will also say it’s possibly one of the most difficult write-ups I have had to do also. Not because it was bad, quite the opposite, it is rather brilliant.

It is more about how to describe that brilliance in easily understood words to the headphone and portable audio crowds because the changes are like nothing I have experienced before in this hobby.

The concept of a ‘lens’ on your music is apt, the idea that dynamic range and how ‘vivid’ your best setup can sound can be improved is relevant. However, you need a revealing setup to get the benefits.

Is it the final step or the fabled ‘end game’? No, because the M Scaler is but one piece in a long chain. Improve other aspects of that chain and it is likely the M Scaler will happily shuffle up another level to match that improvement. I would actually argue it helps everything else get a little closer to being an ‘end game’.

Going modular does retain the shelf life of the M Scaler immeasurably. Not only is my ‘humble’ Qutest DAC transformed but it leaves me wondering what if I had an even better Chord DAC or connected it to a more expansive HiFi speaker system? Something perhaps where the results are more readily detected and shared?

Well, that’s just GAS now, isn’t it? The M Scaler may well be world-class, but my wallet is definitely 3rd rate. Bah humbug!

Chord Hugo M Scaler Specifications

  • PGA: Xilinx XC7A200T
  • Filter tap length: 1,015,808 WTA taps
  • Dimensions: 235 x 40.5 x 236mm (WxHxD)
  • Weight: 2.55kg

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