[DAC/Headphones Amplifier] Burson Conductor Grand Tourer 4
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I just got one of these a few days ago with the loaner tour program. I have some similar stacks to compare it to like the SMSL H400/D400SE and Topping A70Pro/D70Pro Octo and also Sabre versions. The Class A nearest I have is the Singxer SA-1 V2 and the Topping A30Pro when it detects the HD650 which is 300ohm, then goes fully class A mode. I've been using it 4 days just to get over the initial wow factor and swap it for some other things to compare on the same day. qsk78 really covered everything on it in the last amazing review.
The sound is more detailed than other class A amplifiers I've had, no fuzziness or overly smooth sound, crisp and clean. The sound reminds me most of the Gustard X26Pro with the Singxer SA-1 V2. I've tried a variety of headphones so far, Focal Utopia (original not the 2022 which I thought was a little more V shaped), Hifiman Edition XS, Dan Clark Aeon 2 open, Fiio FT3 350 ohm, Sennheiser HD650, and a couple of Beyerdynamics (DT770 and DT880 250 ohm). Any headphone, dynamic or planar was great with it. To test noise floor I used the 18 ohm Moondrop Chu 2 (the same pair Amir did review and measurements on) and I also wouldn't recommend for really sensitive IEMs. If it had a medium gain and a true low gain mode it would really help. For IEMs my first pick is always the Topping L30 II, so plugging one to this for dedicated IEM use is the ideal setup.
Thermals and power consumption: I have a laser thermometer and in a 75F room the temps blowing out the sides were 127F and on top measured 120F. I put it on a slotted monitor riser, to see if airflow helped but it was the same. The feet on this seem to be the right size for maximum airflow.
I have a Sinewave UPS with a power meter in watts, so it's 90w at idle and in operation 96w, this is not something most would want to leave on 24/7. A 100 watt traditional light bulb draws 78 watts, so it's not the end of the world for your electric bill, but worth mentioning since there's no standby mode.
Technicalities: Some things worth knowing is it comes with a 3 year warranty, but it's not transferable. It also mentions no modifications or it's void. It's also important to only use their XLR to RCA cables/adapters which are designed specially for this unit. Don't use off the shelf ones or you'll damage it. This came shipped in high gain mode, but the volume was at zero so no risk. Just check it in the setup menu since you might never need it. The drivers are hosted with a Google drive link, small thing, but I wish they just did a direct download since Google was having technical problems and it took a while to get it (and 3 different browsers, Edge worked best).
Is it worth it? If it's not a financial stretch, you have room on your desk, and enough air conditioning to keep the room cool then yes. The sound is Goldilocks, not too smooth or too bright, they really nailed it. Competition is tough those, the Topping DX9 is right up there at lower cost (and the tacky diagram cover on it). If you like the class A sound/smoothness, it's hard to do better (the Singxer was fun, but I wouldn't keep it for myself, this one I would use for a daily driver easily). It's well made, sounds great, and looks higher end than most of the matte black offerings. The price is premium, but if that's not a deal breaker I recommend it based one how clean it sounds (and effectively unlimited power). There's a Fusion power supply upgrade, with the base power supply it competes with anything else I've heard.
The sound is more detailed than other class A amplifiers I've had, no fuzziness or overly smooth sound, crisp and clean. The sound reminds me most of the Gustard X26Pro with the Singxer SA-1 V2. I've tried a variety of headphones so far, Focal Utopia (original not the 2022 which I thought was a little more V shaped), Hifiman Edition XS, Dan Clark Aeon 2 open, Fiio FT3 350 ohm, Sennheiser HD650, and a couple of Beyerdynamics (DT770 and DT880 250 ohm). Any headphone, dynamic or planar was great with it. To test noise floor I used the 18 ohm Moondrop Chu 2 (the same pair Amir did review and measurements on) and I also wouldn't recommend for really sensitive IEMs. If it had a medium gain and a true low gain mode it would really help. For IEMs my first pick is always the Topping L30 II, so plugging one to this for dedicated IEM use is the ideal setup.
Thermals and power consumption: I have a laser thermometer and in a 75F room the temps blowing out the sides were 127F and on top measured 120F. I put it on a slotted monitor riser, to see if airflow helped but it was the same. The feet on this seem to be the right size for maximum airflow.
I have a Sinewave UPS with a power meter in watts, so it's 90w at idle and in operation 96w, this is not something most would want to leave on 24/7. A 100 watt traditional light bulb draws 78 watts, so it's not the end of the world for your electric bill, but worth mentioning since there's no standby mode.
Technicalities: Some things worth knowing is it comes with a 3 year warranty, but it's not transferable. It also mentions no modifications or it's void. It's also important to only use their XLR to RCA cables/adapters which are designed specially for this unit. Don't use off the shelf ones or you'll damage it. This came shipped in high gain mode, but the volume was at zero so no risk. Just check it in the setup menu since you might never need it. The drivers are hosted with a Google drive link, small thing, but I wish they just did a direct download since Google was having technical problems and it took a while to get it (and 3 different browsers, Edge worked best).
Is it worth it? If it's not a financial stretch, you have room on your desk, and enough air conditioning to keep the room cool then yes. The sound is Goldilocks, not too smooth or too bright, they really nailed it. Competition is tough those, the Topping DX9 is right up there at lower cost (and the tacky diagram cover on it). If you like the class A sound/smoothness, it's hard to do better (the Singxer was fun, but I wouldn't keep it for myself, this one I would use for a daily driver easily). It's well made, sounds great, and looks higher end than most of the matte black offerings. The price is premium, but if that's not a deal breaker I recommend it based one how clean it sounds (and effectively unlimited power). There's a Fusion power supply upgrade, with the base power supply it competes with anything else I've heard.
We continue to study new products from the Australian company.
This time it is the Conductor GT4 (DAC + preamp + headphone amplifier), model year 2024.
Standard Package:
Conductor GT4 with V6 Vivid operational amplifiers, Silent Power 01 power modules and standard switching power supply
Deluxe Package:
Conductor GT4 with V7 Vivid operational amplifiers, Silent Power 02 power modules, and Super Charger 5A PSU
Max Package:
Conductor GT4 with V7 Vivid op-amps, Silent Power 02 power modules and Burson Fusion Core 24V/15A PSU
I got my hands on a Deluxe version with the ability to expand to the Max version using Fusion Core.
SPECIFICATION
All spec details you can find on the official website
DESIGN
The GT4 is currently the company's top-of-the-line device and it combines all of Burson Audio's latest technologies and best practices in digital-to-analog conversion, amplification and power supply.
In fact, the GT4 has the Soloist GT’s amplification section on board, which is independently powered and can deliver up to 10 watts per channel in pure Class A!
As a DAC, two well-known ES9038 chips are used here. One per channel. And this is still the same mobile version of these chips - Q2M, which you can find in Composer and older versions of Conductor. Unlike the previous generation each DAC chip is independently powered and handles only one channel. Burson says that “this new design eliminates cross-channel interference and significantly improves detail retrieval”.
By the way, many people wonder why mobile versions of the ESS chip are used instead of the latest generation of Pro versions. I asked the manufacturer this question when I was the owner of their Composer 3XP DAC several years ago: right implementation is the key.
I remember Composer 3XP very well, and how well the DAC sounded on the single 9038q2m – very naturally, without a hint of a typical "ESS digital flavor” which you can hear in some poor implementations sometimes.
Silent Power Modules (7 pcs.) are responsible for Interference noise filtering.
ABOUT COOLING
The GT4 is probably the most powerful All-in-One device on the market today. According to independent measurements, its characteristics exceed even the declared 10 W at 32 ohms per channel. It generates a huge amount of heat that must be drawn away without extra noise.
Burson uses super quiet and small fans powered by the main board. The fans are mounted on the top cover of the GT4 and draw the heat away through special slots on both sides of the unit. Unlike the Soloist GT with its large fan, the device remains almost silent here. You can hear the operation of the fans getting close to the GT4 and only in case of perfect silence. If we talk about numbers, the dB meter gave an increase of only 1.5-2 dBa at a distance of 5 cm from the device body.
Regarding the heating temperature the GT4 feels comparable to the heating temperature of the Soloist Voyager.
Either quiet but hot, or loud but cool...I personally prefer silence.
MENU. DISPLAY
There is an INPUT section (the first button on the left), which lists all possible ways to connect and switch the device. Everything is intuitive and clear by pictograms.
There is an OUTPUT section (the second button on the left), where the operating modes are: headphone output, headphone output and subwoofer, pre-amp, DAC.
And there is a settings button, where you can select the gain mode (low and high), filters, backlight settings, auto-off, etc.
ABOUT THE SOUND
It happened so that the GT4 came to me shortly before the New Year, and my plans were to go with my family for a week to visit relatives in another city. I couldn't wait to get acquainted with the device, so I took it with me.
Two boxes plus a case with headphones did not take up much space in the trunk. I can't help but note that the Heddphone 2 is equipped with a very convenient and compact travel case.
I used a laptop with Audirvana and integrated Qobuz as a sound source. Unfortunately, later on, I couldn't connect the GT4 to my home system, where the signal source is a Sonnet Hermes streamer as I’m now on Volumio. And with Volumio I have the I2S output only but do not the same input on the GT4. So, I had to stay on Audirvana and usb.
This simple way of connection seems to me more suitable for the GT4 than completely linking it to a desktop setup, leaving room for mobility and moving it within the house or apartment.
So, I will try to tell you about the impressions received from various options and combinations.
Conductor GT4-XLR headphone output. Powered by Supercharger.
To me, the sound of the GT4 is closer to the neutral side, possibly with a slight accent in the bright side, taking the “nature” of ESS company chips into account.
As it should be for ESS, the sound is rich in fine details and nuances with a very good soundstage (as far as the headphones allow), with excellent resolution over the entire frequency range, with a clearly defined and deep bass.
There are no problems with speed and dynamics.
For fans of R2R the treble may sometimes seem even a little accentuated.
I’ve been "sitting" on the R2R DAC for the last 3 years and it took me some time to get used to the GT4’s sound signature. Although, the delta-sigma flavor can be captured only when the GT4 is powered by Supercharger power supply unit.
But even in base, the GT4 sounds very "mature" and precise, overperforming previous generations (from memory), still leaving some room for further growth. And it’s growing...
Conductor GT4-XLR headphone output. Powered by Fusion Core.
When switching to FC, it seems that the sound signature changes slightly to a better balance, evenness, and the overall sound becomes more "analog", more "smooth".
With the transition to FC we also get a blacker background and an increase in the overall quality: the size of the soundstage, especially in depth, the instrument and channel separation, as well as micro nuances. Images get even more “weight”.
As a quick example - the track Karmosin by Tord Gustavsen Trio from the album Being There: long intro of drums and percussion. Switching from SC to FC, I can hear a clearer and more "defined” positioning of instruments, especially in depth. Images of percussion elements get more weight and get more precise borders. Each hit and touch have a more defined individuality, as well as the difference between quiet and loud sounds (wider dynamic range). It is much easier to hear micro details in the background. In addition, there is a feeling that some superfluous noise was cut off, which filled the "space and time" between the instruments and was replaced by the background "blackness".
As we can see, high-quality power supply plays a significant role in improving the sound. Who would doubt it?
I couldn't skip the chance to try the GT4 in combination with the Soloist Voyager. And since I have only one Fusion Core PSU, I got only two possible combinations for comparison.
GT4 w/ Fusion Core + Soloist Voyager w/Supercharger
First, the Fusion Core powers the GT4 in DAC mode, while the amplifier is powered by Supercharger.
To my ears, there is no huge difference. Except that the Voyager version builds the soundstage a little more spacious and a little wider. I didn't notice any significant technical or musical differences.
This proves that Burson has done a really good job with the GT4's amplification section.
GT4 w/ Supercharger + Soloist Voyager w/ Fusion Core
Next, we connect the Fusion Core to the amplifier and give the Supercharger to the GT4. And here the presence of Voyager now makes a difference. The soundstage becomes even more spacious and complex, plus some technicalities related to separation and positioning of instruments get more vivid.
And what would happen if you add one more Fusion Core to this combination? Unfortunately, I couldn't get an answer to this question. You can only guess about further improvements of the sound.
BLUETOOTH
By the way, now the Gt4, thanks to Qualcomm CSR 8675, supports the LDAC codec. It works great.
If you do not want to pull cables, but just listen to your favorite music without “tearing it up for molecules”, then such a mode will perfectly do the job!
ROON READY
The GT4 is Roon Ready (Roon Tested) and works with all Roon Ready devices.
CONCLUSION
Well, the GT4 turned out well. Recalling another generation of DAC/amps (ex. the Conductor 3X Reference) the new flagship brings even more naturalness, precision and dynamics to the sound.
To me the device is genre-wise universal. I listened to a lot of things, from classics to the latest albums from Ulcerate. There were no problems neither with accuracy and precision nor with speed.
I can definitely recommend GT4 to those who are looking for an all-in-one desktop solution. Such a device can completely close the issue.
Using the Fusion Core with the GT4 is another step up. Therefore, there is a good reason to consider such a combination, if not now but for the future.
Definitely the GT4 is not cheap, but if it closes your issue, then eventually there will be significant savings compared to the cost of building a multi component setup.
It also works if there is a need to have a high-quality source at another location (ex. your office) but in a compact size and with a minimum of components.
I think there may be some other options where the GT4 will adequately cover all the needs of a critical listener.
Here is my video review in Russian
This time it is the Conductor GT4 (DAC + preamp + headphone amplifier), model year 2024.
Standard Package:
Conductor GT4 with V6 Vivid operational amplifiers, Silent Power 01 power modules and standard switching power supply
Deluxe Package:
Conductor GT4 with V7 Vivid operational amplifiers, Silent Power 02 power modules, and Super Charger 5A PSU
Max Package:
Conductor GT4 with V7 Vivid op-amps, Silent Power 02 power modules and Burson Fusion Core 24V/15A PSU
I got my hands on a Deluxe version with the ability to expand to the Max version using Fusion Core.
SPECIFICATION
All spec details you can find on the official website
DESIGN
The GT4 is currently the company's top-of-the-line device and it combines all of Burson Audio's latest technologies and best practices in digital-to-analog conversion, amplification and power supply.
In fact, the GT4 has the Soloist GT’s amplification section on board, which is independently powered and can deliver up to 10 watts per channel in pure Class A!
As a DAC, two well-known ES9038 chips are used here. One per channel. And this is still the same mobile version of these chips - Q2M, which you can find in Composer and older versions of Conductor. Unlike the previous generation each DAC chip is independently powered and handles only one channel. Burson says that “this new design eliminates cross-channel interference and significantly improves detail retrieval”.
By the way, many people wonder why mobile versions of the ESS chip are used instead of the latest generation of Pro versions. I asked the manufacturer this question when I was the owner of their Composer 3XP DAC several years ago: right implementation is the key.
I remember Composer 3XP very well, and how well the DAC sounded on the single 9038q2m – very naturally, without a hint of a typical "ESS digital flavor” which you can hear in some poor implementations sometimes.
Silent Power Modules (7 pcs.) are responsible for Interference noise filtering.
ABOUT COOLING
The GT4 is probably the most powerful All-in-One device on the market today. According to independent measurements, its characteristics exceed even the declared 10 W at 32 ohms per channel. It generates a huge amount of heat that must be drawn away without extra noise.
Burson uses super quiet and small fans powered by the main board. The fans are mounted on the top cover of the GT4 and draw the heat away through special slots on both sides of the unit. Unlike the Soloist GT with its large fan, the device remains almost silent here. You can hear the operation of the fans getting close to the GT4 and only in case of perfect silence. If we talk about numbers, the dB meter gave an increase of only 1.5-2 dBa at a distance of 5 cm from the device body.
Regarding the heating temperature the GT4 feels comparable to the heating temperature of the Soloist Voyager.
Either quiet but hot, or loud but cool...I personally prefer silence.
MENU. DISPLAY
There is an INPUT section (the first button on the left), which lists all possible ways to connect and switch the device. Everything is intuitive and clear by pictograms.
There is an OUTPUT section (the second button on the left), where the operating modes are: headphone output, headphone output and subwoofer, pre-amp, DAC.
And there is a settings button, where you can select the gain mode (low and high), filters, backlight settings, auto-off, etc.
ABOUT THE SOUND
It happened so that the GT4 came to me shortly before the New Year, and my plans were to go with my family for a week to visit relatives in another city. I couldn't wait to get acquainted with the device, so I took it with me.
Two boxes plus a case with headphones did not take up much space in the trunk. I can't help but note that the Heddphone 2 is equipped with a very convenient and compact travel case.
I used a laptop with Audirvana and integrated Qobuz as a sound source. Unfortunately, later on, I couldn't connect the GT4 to my home system, where the signal source is a Sonnet Hermes streamer as I’m now on Volumio. And with Volumio I have the I2S output only but do not the same input on the GT4. So, I had to stay on Audirvana and usb.
This simple way of connection seems to me more suitable for the GT4 than completely linking it to a desktop setup, leaving room for mobility and moving it within the house or apartment.
So, I will try to tell you about the impressions received from various options and combinations.
Conductor GT4-XLR headphone output. Powered by Supercharger.
To me, the sound of the GT4 is closer to the neutral side, possibly with a slight accent in the bright side, taking the “nature” of ESS company chips into account.
As it should be for ESS, the sound is rich in fine details and nuances with a very good soundstage (as far as the headphones allow), with excellent resolution over the entire frequency range, with a clearly defined and deep bass.
There are no problems with speed and dynamics.
For fans of R2R the treble may sometimes seem even a little accentuated.
I’ve been "sitting" on the R2R DAC for the last 3 years and it took me some time to get used to the GT4’s sound signature. Although, the delta-sigma flavor can be captured only when the GT4 is powered by Supercharger power supply unit.
But even in base, the GT4 sounds very "mature" and precise, overperforming previous generations (from memory), still leaving some room for further growth. And it’s growing...
Conductor GT4-XLR headphone output. Powered by Fusion Core.
When switching to FC, it seems that the sound signature changes slightly to a better balance, evenness, and the overall sound becomes more "analog", more "smooth".
With the transition to FC we also get a blacker background and an increase in the overall quality: the size of the soundstage, especially in depth, the instrument and channel separation, as well as micro nuances. Images get even more “weight”.
As a quick example - the track Karmosin by Tord Gustavsen Trio from the album Being There: long intro of drums and percussion. Switching from SC to FC, I can hear a clearer and more "defined” positioning of instruments, especially in depth. Images of percussion elements get more weight and get more precise borders. Each hit and touch have a more defined individuality, as well as the difference between quiet and loud sounds (wider dynamic range). It is much easier to hear micro details in the background. In addition, there is a feeling that some superfluous noise was cut off, which filled the "space and time" between the instruments and was replaced by the background "blackness".
As we can see, high-quality power supply plays a significant role in improving the sound. Who would doubt it?
I couldn't skip the chance to try the GT4 in combination with the Soloist Voyager. And since I have only one Fusion Core PSU, I got only two possible combinations for comparison.
GT4 w/ Fusion Core + Soloist Voyager w/Supercharger
First, the Fusion Core powers the GT4 in DAC mode, while the amplifier is powered by Supercharger.
To my ears, there is no huge difference. Except that the Voyager version builds the soundstage a little more spacious and a little wider. I didn't notice any significant technical or musical differences.
This proves that Burson has done a really good job with the GT4's amplification section.
GT4 w/ Supercharger + Soloist Voyager w/ Fusion Core
Next, we connect the Fusion Core to the amplifier and give the Supercharger to the GT4. And here the presence of Voyager now makes a difference. The soundstage becomes even more spacious and complex, plus some technicalities related to separation and positioning of instruments get more vivid.
And what would happen if you add one more Fusion Core to this combination? Unfortunately, I couldn't get an answer to this question. You can only guess about further improvements of the sound.
BLUETOOTH
By the way, now the Gt4, thanks to Qualcomm CSR 8675, supports the LDAC codec. It works great.
If you do not want to pull cables, but just listen to your favorite music without “tearing it up for molecules”, then such a mode will perfectly do the job!
ROON READY
The GT4 is Roon Ready (Roon Tested) and works with all Roon Ready devices.
CONCLUSION
Well, the GT4 turned out well. Recalling another generation of DAC/amps (ex. the Conductor 3X Reference) the new flagship brings even more naturalness, precision and dynamics to the sound.
To me the device is genre-wise universal. I listened to a lot of things, from classics to the latest albums from Ulcerate. There were no problems neither with accuracy and precision nor with speed.
I can definitely recommend GT4 to those who are looking for an all-in-one desktop solution. Such a device can completely close the issue.
Using the Fusion Core with the GT4 is another step up. Therefore, there is a good reason to consider such a combination, if not now but for the future.
Definitely the GT4 is not cheap, but if it closes your issue, then eventually there will be significant savings compared to the cost of building a multi component setup.
It also works if there is a need to have a high-quality source at another location (ex. your office) but in a compact size and with a minimum of components.
I think there may be some other options where the GT4 will adequately cover all the needs of a critical listener.
Here is my video review in Russian
aro
It is very nice, but would it be worth an upgrade from R180x?
qsk78
Well, I remember Conductor 3XR. I would say that the FT4 +FC is a huge upgrade, in case you are ready to pay for this upgrade 
Hello everyone! I was happy when Burson contacted me back in July about the possibility to ship me one unit of their new Conductor GT4 DAC/headamp combo for reviewing it. I was even happier last week when the package actually arrived at my door, mostly because I was very curious to check how it is different from the previous Conductor 3X version.
Packaging is top notch, something Burson used to do since their first Conductor. The double-boxing plus the roughed corners from inside ensure worry free shipping worldwide. In my case the package had zero scratches or bents, probably DHL helped here too.
I quickly grabbed my test laptop, an Apple Silicon MacBook Pro, recently upgraded to latest Sequoia, then I connected Conductor GT4 via the original USB-C cable. In a few seconds it was seen by the MacOS as "Burson Audio" USB transport, so no drivers are needed for MacOS. Have it also tested on Intel MacBook Pro on Sonoma, then on Windows 10 and Windows 11 (ASIO drivers too) and I had no issues with the plug & play installation and audio playback.
On MacOS it shows as Burson Audio device
So, I gave it a listen for a few hours on various headphones I had around and I quickly realised that the sound coming from the GT4 is less fatiguing and I was able to listen for hours and hours, even with bright headphones like Grado. Despite being less fatiguing, I haven’t noticed any details loss, probably the V7 Pro helps here a lot. I’ve listened to a lot of rock songs and even on more compressed tracks I haven’t felt like I should take a break from listening, instead I felt that I should increase the volume even more. The soundstage is huge, probably due to the very good crosstalk figure...or maybe it is the V7 Pro Vivid that comes in handy here? The final sound is neutral to warm, but rich in details and the dynamics are sky high, especially on louder volumes. What I'm hearing sounds more...balanced, but clean and detailed at the same time, perhaps not extremely detailed, but in a good way.
Burson Conductor Grand Tourer 4
Background is completely dark with all the planar and dynamic headphones I’ve tested. When switching to very sensitive IEMs a slight hiss could become audible, but it really depends on IEMs impedance and sensitivity. In my case, I was testing for the hiss with 16 Ohms 130dB SPL sensitivity IEMs and some hiss was heard between the tracks, but nothing to disturb me. However, the slight hiss noise perceived is still lower than the noise generated by my AirPods 2 Pro with ANC turned On. So, I’d say that, given the huge amount of power GT4 delivers, my very sensitive IEM’s hiss is nothing to be worried about.
In the following image I managed to identify and circle around all the stages from Conductor’s motherboard.
On MacOS it shows as Burson Audio device
So, I gave it a listen for a few hours on various headphones I had around and I quickly realised that the sound coming from the GT4 is less fatiguing and I was able to listen for hours and hours, even with bright headphones like Grado. Despite being less fatiguing, I haven’t noticed any details loss, probably the V7 Pro helps here a lot. I’ve listened to a lot of rock songs and even on more compressed tracks I haven’t felt like I should take a break from listening, instead I felt that I should increase the volume even more. The soundstage is huge, probably due to the very good crosstalk figure...or maybe it is the V7 Pro Vivid that comes in handy here? The final sound is neutral to warm, but rich in details and the dynamics are sky high, especially on louder volumes. What I'm hearing sounds more...balanced, but clean and detailed at the same time, perhaps not extremely detailed, but in a good way.
Burson Conductor Grand Tourer 4
Background is completely dark with all the planar and dynamic headphones I’ve tested. When switching to very sensitive IEMs a slight hiss could become audible, but it really depends on IEMs impedance and sensitivity. In my case, I was testing for the hiss with 16 Ohms 130dB SPL sensitivity IEMs and some hiss was heard between the tracks, but nothing to disturb me. However, the slight hiss noise perceived is still lower than the noise generated by my AirPods 2 Pro with ANC turned On. So, I’d say that, given the huge amount of power GT4 delivers, my very sensitive IEM’s hiss is nothing to be worried about.
In the following image I managed to identify and circle around all the stages from Conductor’s motherboard.
The green surrounded part is the one containing digital stages. We can see an USB-C transport card, based on the low latency XMOS xCORE-200 Series microcontroller which decodes the USB digital signals and passes them to the DAC chips.
The XMOS microcontroller from the USB-C digital transport board
On the same "USB transport" board I can see a CMedia CM6327A chip which is a high performance microphone Analogue to Digital Converter that handles microphone input, to be able to control its output volume and to pass it over to the microphone’s output jack from the back.
CMedia CM6327A - microphone ADC
Another ADC chip can be spotted, this time on the motherboard: the Cirrus Logic CS5351, that transforms the analogue inputs like RCA and XLR from the rear into digital signals that are then used to get their volume adjusted by the two DAC chips mentioned above, this way creating a very clever preamplifier stage. I’ve seen it in the past in Conductor 3X headphones amplifier where Burson used a similar ADC chip for the same purpose.
Cirrus Logic CS5351 - Analogue inputs ADC
Underneath USB transport card there are two ES9038Q2M DAC chips that are taking care of transforming the digital audio signal in analog waves, feeding the input stage based on V7 Pro Vivid operational amplifiers.
One of the two ES9038Q2M DAC chips
Clean power to the two DAC chips is provided by a couple of low-noise LT3045 from Analogue Devices, but also up-the-hill the circuit there are other electrically isolated power stages cleaning even more the power signal from any unwanted EMI/RFI noises.
DAC chips, low-noise regulators, the TCXO crystal, gold-plated slow-blow fuse
BlueTooth 5.0+ aptX high-resolution audio is based on the "Premium tier" Qualcomm® CSR8675 chip that delivers up to 24-bit/192KHz audio over Bluetooth and aptX HD as well. I had no problems streaming Tidal via my test phones iPhone 15 Pro Max and Samsung S24.
24-bit/192kHz BlueTooth 5.0+ aptX high-resolution Qualcomm® CSR8675 chip
An ALTERA EPM3064A EEPROM–based programmable logic device (PLD, see https://en.wikipedia.org/wiki/Programmable_logic_device for details) is programmed to instruct the GT4 how to properly operate internally.
ALTERA EPM3064A EEPROM memory
The blue part contains the Input / Output connectors. I counted thirteen Panasonic relays on this stage, quite a lot and not easy to control via software, so Burson came up with aid from a couple of NXP PCF8574AT I/O expanders. This way GT4 is able to open and close each of these relays, depending on the inputs and outputs chosen from the front OLED panel.
NXP PCF8574AT I/O expanders
The XMOS microcontroller from the USB-C digital transport board
On the same "USB transport" board I can see a CMedia CM6327A chip which is a high performance microphone Analogue to Digital Converter that handles microphone input, to be able to control its output volume and to pass it over to the microphone’s output jack from the back.
CMedia CM6327A - microphone ADC
Another ADC chip can be spotted, this time on the motherboard: the Cirrus Logic CS5351, that transforms the analogue inputs like RCA and XLR from the rear into digital signals that are then used to get their volume adjusted by the two DAC chips mentioned above, this way creating a very clever preamplifier stage. I’ve seen it in the past in Conductor 3X headphones amplifier where Burson used a similar ADC chip for the same purpose.
Cirrus Logic CS5351 - Analogue inputs ADC
Underneath USB transport card there are two ES9038Q2M DAC chips that are taking care of transforming the digital audio signal in analog waves, feeding the input stage based on V7 Pro Vivid operational amplifiers.
One of the two ES9038Q2M DAC chips
Clean power to the two DAC chips is provided by a couple of low-noise LT3045 from Analogue Devices, but also up-the-hill the circuit there are other electrically isolated power stages cleaning even more the power signal from any unwanted EMI/RFI noises.
DAC chips, low-noise regulators, the TCXO crystal, gold-plated slow-blow fuse
BlueTooth 5.0+ aptX high-resolution audio is based on the "Premium tier" Qualcomm® CSR8675 chip that delivers up to 24-bit/192KHz audio over Bluetooth and aptX HD as well. I had no problems streaming Tidal via my test phones iPhone 15 Pro Max and Samsung S24.
24-bit/192kHz BlueTooth 5.0+ aptX high-resolution Qualcomm® CSR8675 chip
An ALTERA EPM3064A EEPROM–based programmable logic device (PLD, see https://en.wikipedia.org/wiki/Programmable_logic_device for details) is programmed to instruct the GT4 how to properly operate internally.
ALTERA EPM3064A EEPROM memory
The blue part contains the Input / Output connectors. I counted thirteen Panasonic relays on this stage, quite a lot and not easy to control via software, so Burson came up with aid from a couple of NXP PCF8574AT I/O expanders. This way GT4 is able to open and close each of these relays, depending on the inputs and outputs chosen from the front OLED panel.
NXP PCF8574AT I/O expanders
The analogue audio stages, Input, Gain and Pre-Amp, are created around six audiophiles operational amplifiers, the V7 Pro Vivid, launched earlier this year. These op-amps will ensure a clean and detailed sound, with fast transients and deep bass, with a little bit of warmth being felt though, the specific sound of all Burson products actually.
The six V7 Pro Vivid transistored op-amps
The red circled part contains the analogue audio amplifiers. Being a true fully-balanced headphone amplifier, Conductor GT4 contains inside four distinct amplifiers, two for each output channel. Each such amplifier has ten transistors, first eight of them being small bi-polars which are driving the final two big transistors from the output stage.
The powerful output stage is created around eight beefy bi-polar transistors from ON Semiconductor2: MJE15032G (NPN) / MJE15033G (PNP), a newer and powerful alternative of the obsolete 2SA1939 / 2SC5171, packed in the same TO-220 case. Each of these transistors are able to push up to 8 Amperes and can dissipate up to 50 Watts, so we usually find such transistors in low to mid power speakers amplifiers able to deliver between 35 to 70 Watts per channel at 4-8 Ohms.
ON Semiconductor2 MJE15032G / MJE15033G powerful output transistors biased in Class A
The output transistors are working in Class-A 100% of the operating time, meaning that the amplifier will deliver audio natively in Class-A, from the lowest signal levels to the maximum power of the amplifier.
Burson Conductor Grand Tourer 4 + Fusion Core combo has enough juice to drive two planar headphones simultaneously
Running the output stage fully in Class-A generates a lot of power consumption (I measured about 75 Watts with no music playing), meaning higher operating temperature, hence the outer case will heat up quite well. I was able to measure between 50-53C on the sides and between 40-42C on the top of the case, in a room with a rather constant 22-23C without in-room ventilation. This is a rather high operating temperature for a headphones amplifier, but it’s very normal when talking about Class-A output stage, so definitely not a concerning temperature, for sure.
Case temperatures while operating
The six V7 Pro Vivid transistored op-amps
The red circled part contains the analogue audio amplifiers. Being a true fully-balanced headphone amplifier, Conductor GT4 contains inside four distinct amplifiers, two for each output channel. Each such amplifier has ten transistors, first eight of them being small bi-polars which are driving the final two big transistors from the output stage.
The powerful output stage is created around eight beefy bi-polar transistors from ON Semiconductor2: MJE15032G (NPN) / MJE15033G (PNP), a newer and powerful alternative of the obsolete 2SA1939 / 2SC5171, packed in the same TO-220 case. Each of these transistors are able to push up to 8 Amperes and can dissipate up to 50 Watts, so we usually find such transistors in low to mid power speakers amplifiers able to deliver between 35 to 70 Watts per channel at 4-8 Ohms.
ON Semiconductor2 MJE15032G / MJE15033G powerful output transistors biased in Class A
The output transistors are working in Class-A 100% of the operating time, meaning that the amplifier will deliver audio natively in Class-A, from the lowest signal levels to the maximum power of the amplifier.
Burson Conductor Grand Tourer 4 + Fusion Core combo has enough juice to drive two planar headphones simultaneously
Running the output stage fully in Class-A generates a lot of power consumption (I measured about 75 Watts with no music playing), meaning higher operating temperature, hence the outer case will heat up quite well. I was able to measure between 50-53C on the sides and between 40-42C on the top of the case, in a room with a rather constant 22-23C without in-room ventilation. This is a rather high operating temperature for a headphones amplifier, but it’s very normal when talking about Class-A output stage, so definitely not a concerning temperature, for sure.
Case temperatures while operating
The cooling of the output transistors is quite difficult to do in a device having such a low height, but Burson Engineers have already found a solution that has been implemented in other Burson devices previously. Solution consists in tidying all the eight power transistors on the bottom aluminum plate that acts as a heatsink. More than that, Conductor GT4 benefits from completely noiseless active cooling and on the bottom of the case there are several small vents from where cold air from the room gets sucked inside the case. This way the internals will never get overheated and the aluminum case will stay within normal temperatures while operating.
The two small & noiseless fans that are blowing hot air outside GT4
The bottom of the case acts as a huge heatsink with small vents for in-room air intake
The thermal pads from the heatsink and the eight powerful transistors from output stage.
The two small & noiseless fans that are blowing hot air outside GT4
The bottom of the case acts as a huge heatsink with small vents for in-room air intake
The thermal pads from the heatsink and the eight powerful transistors from output stage.
In the orange circled part I can see six new Max Current Power Modules inside the GT4, recently developed by Burson for increasing power isolation and stage separation across multiple digital and analogue stages, meaning that noises that might occur within any of these stages will not propagate further to other stages. These new modules are designed around the low-noise SCT2650 LDO DC-DC regulator, replacing TPS54560 used on the Soloist 3X Grand Tourer. This LDO regulator is offering a more consistent performance over the previous one used in Soloist 3X GT and it also offers a higher maximum intensity of 8 Amperes peaks, which can be beneficial for the four amplifiers inside.
The bigger deal aspect is the stacking of these power modules, so no PCB and no case will need to increase in size. This ensures once again that each audio stage and each GT4 function benefits of its own dedicated power supply, minimising any possible noise interference. And, as we all know about audio equipment, the more it has separated power supplies, the better the final audible performance and specs are. I am, personally, more than happy to see an audio device where each stage gets its own internal power supply, instead of one big PSU sharing the power across all stages.
Talking about power modules, I counted no less than seven Silent Power (see https://www.bursonaudio.com/shop/sp02-upgrade-kit/) voltage regulating modules installed inside Conductor GT4, so two more than there are installed in the Voyager headamp. These modules consist of extremely low-noise voltage regulators that practically eliminate any possible EMI/RFI noises that might be fed from the mains power supply, ensuring a clean audio output at the end of the headphones plugs.
The seven Silent Power regulators
In the yellow part, near the front plate, we have a headphones protection circuitry near the output plugs that kicks in if an internal damage happens, for example in case a transistor gets broken and a high level of DC current tries to get to the headphones outputs. The protection circuitry is designed around the C1237HA integrated chip which is directly connected to a couple of relays, one for the two 3.5 & 6.3mm jacks and the other one for the 4-pin XLR. If something bad happens then the protection will disconnect the headphones plugs by opening the two output relays from above.
Headphones protection circuitry
There’s also a small InfraRed optical protection board that senses if the top cover is lifted off or not. Conductor GT4 will stop operating and enter in protection mode if the top case is removed or if one of the two inner fans gets defective. Getting out of the protection mode can be done by pressing on the Power button for at least 5-6 seconds, but if the defect was not resolved it will enter into the same protection immediately, case where Burson Support needs to be contacted.
A few audio measurements done with Cosmos E1DA ADC (32bit/-120dB THD+N) and with PicoScope oscilloscope.
Conductor GT4 - DAC XLR out - THD+N better than -100 dB
Conductor GT4 driving 33 Ohms load on 4-pin XLR headphones-out - THD+N close to -96 dB
Conductor GT4 driving 600 Ohms load on 4-pin XLR headphones-out - THD+N close to -94 dB
Conductor GT4 driving 33 Ohms load on 4-pin XLR headphones-out - 11.5 Watts output power
Conductor GT4 driving 600 Ohms load on 4-pin XLR headphones out - 0.95 Watts output power
The bigger deal aspect is the stacking of these power modules, so no PCB and no case will need to increase in size. This ensures once again that each audio stage and each GT4 function benefits of its own dedicated power supply, minimising any possible noise interference. And, as we all know about audio equipment, the more it has separated power supplies, the better the final audible performance and specs are. I am, personally, more than happy to see an audio device where each stage gets its own internal power supply, instead of one big PSU sharing the power across all stages.
Talking about power modules, I counted no less than seven Silent Power (see https://www.bursonaudio.com/shop/sp02-upgrade-kit/) voltage regulating modules installed inside Conductor GT4, so two more than there are installed in the Voyager headamp. These modules consist of extremely low-noise voltage regulators that practically eliminate any possible EMI/RFI noises that might be fed from the mains power supply, ensuring a clean audio output at the end of the headphones plugs.
The seven Silent Power regulators
In the yellow part, near the front plate, we have a headphones protection circuitry near the output plugs that kicks in if an internal damage happens, for example in case a transistor gets broken and a high level of DC current tries to get to the headphones outputs. The protection circuitry is designed around the C1237HA integrated chip which is directly connected to a couple of relays, one for the two 3.5 & 6.3mm jacks and the other one for the 4-pin XLR. If something bad happens then the protection will disconnect the headphones plugs by opening the two output relays from above.
Headphones protection circuitry
There’s also a small InfraRed optical protection board that senses if the top cover is lifted off or not. Conductor GT4 will stop operating and enter in protection mode if the top case is removed or if one of the two inner fans gets defective. Getting out of the protection mode can be done by pressing on the Power button for at least 5-6 seconds, but if the defect was not resolved it will enter into the same protection immediately, case where Burson Support needs to be contacted.
A few audio measurements done with Cosmos E1DA ADC (32bit/-120dB THD+N) and with PicoScope oscilloscope.
Conductor GT4 - DAC XLR out - THD+N better than -100 dB
Conductor GT4 driving 33 Ohms load on 4-pin XLR headphones-out - THD+N close to -96 dB
Conductor GT4 driving 600 Ohms load on 4-pin XLR headphones-out - THD+N close to -94 dB
Conductor GT4 driving 33 Ohms load on 4-pin XLR headphones-out - 11.5 Watts output power
Conductor GT4 driving 600 Ohms load on 4-pin XLR headphones out - 0.95 Watts output power
Stand-by power drawn from the mains socket is 0 W (zero Watts) making the GT4 an eco-friendly device when it's turned off, while its idling power consumption is around 92-93 W at power-On and is lowering down to 86-88 W after a few minutes, a value that is higher than the 74 W I was measuring on the Soloist 3X GT 2023. With hard to drive cans, the power consumption may rise with a few more Watts, but still way below the 360 W limit of the Fusion Core power supply or the 120 W limit of the Super Charger or of the standard power supply, so any of these three PSU will be able to properly drive the Conductor GT4 to its full power. Of course, the more powerful and lower-noise Fusion Core is definitely recommended.
Conclusion: An insanely powerful Class A fully balanced headphone amplifier linked to a dual DAC driven by six V7 Pro Vivid transistorized op-amps. With this amount of power this combo will probably drive all headphone out there at the well-known Burson audiophile quality.
Conclusion: An insanely powerful Class A fully balanced headphone amplifier linked to a dual DAC driven by six V7 Pro Vivid transistorized op-amps. With this amount of power this combo will probably drive all headphone out there at the well-known Burson audiophile quality.
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