Introduction:

If you have have followed the Chord Hugo2 thread on Head-Fi, you might have occasionally seen members ask if they needed to add an amp to their Hugo2. Most often than not, the typical reply from happy Hugo2 owners has been, ‘Why add an amp and lose the transparency?’. While I typically discourage people from adding unnecessary equipment to their chain, I am also a proponent of headphone amplifiers, when your headphone could benefit from it. And that applies if your DAC is a Hugo2 as well. So when I see people discouraging others from trying an amplifier with their Hugo2, I feel they are not giving the right advise. But I can’t blame them, as Chord themselves market their product to be capable of driving some demanding headphones. You can see a picture of an Audeze LCD-4 paired with the Hugo2 on the product page. Plus, this isn’t a simple issue where one answer fits all, as it would depend on your headphone. So what I did was, try various headphones and IEMs with and without a headphone amplifier in the chain, fed by Hugo2 and analysed if adding an amp was beneficial or detrimental. After testing through a few amplifiers and many headphones/IEMs I would like to share my observations. Please note that these are purely subjective opinions based on my personal experience.

Chord Hugo2 – A DAC-Amp That Isn’t:

Before I dive into the actual subject of this article, let’s take a second here to understand a certain detail about the Hugo2. If you are reading this article, I presume you are fairly familiar with, what a Hugo2 is, and what it can/cannot do. But what some of you might not know is, unlike most DAC-Amps, Hugo2 doesn’t have an analog Amp stage. Hugo2’s gain/volume is adjusted in the digital stage. All it rather has, is a simple analog stage, to which, the Headphone Outs and Line Out are connected.  What this means is, when you are connecting an external headphone amplifier to the Hugo2 via Line Out, you are not really bypassing Hugo2’s internal amp, as there isn’t one to begin with. So adding an amp to the chain fed by Hugo2 is simply an addition and not a substitution. This is handy because, you know how the Hugo2 sounds, and any changes to the sound when an amp is added to the chain can be chalked up as the sound characteristics of the amp.

Audio Chain and Gears Used:

Audio Chain: MacBook Pro (JRMC)-> Chord Hugo2 -> Headphone Amplifier -> Headphones/IEMs

Headphone Amplifiers: Schiit Lyr 3, Eddie Current Black Widow 2, Massdrop EC ZDT Jr.

Headphones/IEMs: As I stated in the introduction, the benefit from an amp, or the lack thereof, came down to the headphone being used. For the sake of this article, lets categorise my headphones and IEMs into the following 3 buckets.

1. Heavy-weights: HD800, HD650
2. Medium-weights: MrSpeakers AFO, Audeze LCD 2C
3. Light-weights: Audeze LCD-i4, EE Phantom, Sennheiser IE800, IE80S, FLC 8N

Observations:

Positive Changes After Adding an Amp: 

• Improved Bass Slam
• Larger Soundstage
• Bigger Instrument and Vocal Images 
• Improved Macro-Dynamics
• Effortless Presentation

When an amp of good quality was introduced in the chain, these improvements were consistent across all 3 classes of headphones. The Heavy-weights exhibited a marked improvement in all these aspects to a point that, I couldn’t go back to listening to these headphones straight out of Hugo2. What this resulted in was a more realistic and life-like presentation. The Medium-weights and the Light-weights, while they displayed similar improvements, they didn’t sound under-driven when connected to the Hugo2 directly. In fact, they sounded very good directly out of the Hugo2. But I found myself constantly adding the amp, at least for the Medium-weights. As I mostly use the Light-weights when I am not at my desk, I was fine listening to them directly out of the Hugo2.

Negative Changes After Adding an Amp:

• Slight Loss of Background Blackness
• Introduction of Power Related Noise
• Channel Imbalance

This was very interesting because, the Medium-weights were the least impacted by the negative changes. On the one end, Light-weights had channel imbalance issues below 8 o’ clock on the volume pot and were picking up power related noise in the form of humming/buzzing. On the other end, for certain albums, the Heavy-weights needed the volume pot to be turned beyond 12 o’ clock, at which point, the noise from the power sockets were quite high, that the headphones picked up these noises in the form of humming/buzzing. But this was really an issue with the power sockets and house’s power cabling. On some sockets, Heavy-weights did not pick up hum/buzz until reaching the max limit on the volume pot. But the loss of blackness in the background was experienced with all 3 classes of headphones.

Amp-Dependent Changes: 

• Transparency
• Resolution & Micro-Details
• Depth & Layering
• Tonal-Shift

One misleading idea that Chord and its fanboys have propagated in the forums is, that adding an amp to the Hugo2 will impact the transparency.  It is misleading because, there are plenty of good amps out there that don’t impact the transparency. The same goes with these other aspects too. While price is not a direct indicator of performance, I often found that affordable amps weren’t able to keep up in these aspects. For example, the EC Black Widow 2 did a better job at all these aspects than the Schiit Lyr 3. That is not to say that all expensive amps are great either. Make sure you do a lot of research before deciding on an amp. While transparency is dependent on tonal accuracy, slight tonal shifts don’t really affect transparency. Most good amps, won’t have a complete tonal shifts.

Conclusion:

In my experience, I found that adding an amp brought in some welcome benefits to the sound. The 300-Ohm Sennheisers in particular benefitted the most from an amp. While they did not feel underdriven from the Hugo2, an amp did a better job of opening up their potentials. While IEMs displayed those benefits too, they had channel imbalance issues and were prone to picking up noise, that made them not so ideal to use with a desktop amp. The planar headphones I tried were kind of agnostic in nature. Meaning, they didn’t really need a desktop amp to open up, but the improvement with an amp in the chain was quite apparent.  I feel the ‘loss in transparency’ idea has been overblown and his discouraging many users from trying an amp in the chain. If you are Hugo2 owner and have full-size/not-so-efficient headphones and have been contemplating about getting an amp, I would highly encourage you to do so. But please do some due diligence to pick up a good amp.

Update June 20, 2019: I have restructured the article, so that the headphone dependency factor has been included in the ‘Observation’ section, which provides better context.