The Muse HiFi M5 Ultra was kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links.
The regular price of the M5 Ultra is $299 but HiFiGo is currently running a discount promotion that lowers it to $195.
Muse HiFi
Muse HiFi is a young audio brand known for producing high-performance portable DAC/amps and IEMs. Since emerging around 2022, the company has gained attention for its technical approach, using high quality DAC chipsets and even hybrid tube-transistor amplification in compact devices. Some known products are the Power earphones and the M4 portable USB DAC/amp.
Muse HiFi M5 Ultra
The Muse HiFi M5 Ultra is a portable DAC and headphone amplifier with USB type-C and Bluetooth connectivity. It has a tube-hybrid architecture with a user-selectable tube stage that is based on two Raytheon JAN6418 military-grade NOS pentode tubes. In order to minimize microphonic noise, Muse HiFi has devised a shock absorber solution with customized rubber components and suspensions.
Muse HiFi uses a custom edition of the popular ES9038Q2M DAC chip that was optimized in collaboration with ESS to work in tandem with its tube stage. This architecture, which was eventually named “6418”, solves the interference caused by the Bluetooth signal transmission and ensures a clean output free from any background and current noise interference.
Bluetooth connectivity is handled by Qualcomm’s QCC5125 chipset that supports the high-resolution audio codecs LDAC and AptX Adaptive. Additionally the M5 Ultra is equipped with dual independent Accusilicon AS318B series high-precision ultra-low jitter clocks to ensure clean and clear audio signal processing.
Accessories
The M5 Ultra is generously accessorised. The drawer-like package, which also doubles as a showcase, includes high quality USB A to C, C to C and C to Lighting cables, a USB adapter and a premium protective case made of leather. Everything you are going to need is already included.
Design and build quality
The M5 Ultra has a plain rectangularly shaped chassis made of aluminum alloy with a small monochrome display at the top and a large sized frame that allows a view of the internal board. The overall design concept resembles the Questyle CMA18 Portable. Not sure who is copying who as these devices have been around the same time.
The body of the M5 Ultra has rounded corners and smooth edges making it easy to handle and use. All buttons, which are also made of aluminum, are conveniently located at the right side. The left side has a perforated grill with cellular patterns that reveal the two glowing tubes and let them vent. The front and back panels are covered with premium looking tempered glass.
The Muse HiFi M5 Ultra is exceptionally well made with a minimalistic industrial design that is very attractive. The only thing to note is that the buttons are not that firmly attached so you can hear them rattle when you shake the device.
Measuring 204x167x68mm and weighing about 567g, the M5 Ultra is portable enough to carry in a pocket but not that lightweight as similar competitive devices. As an example the Cayin RU9 measures 100x70x15mm and weighs 150g, but the downside is that it houses a lower capacity battery.
UI and operation
Muse HiFi has designed the M5 Ultra with a simple operation logic without second and third layer menus. All functions and their current state are simultaneously displayed on the screen, together with the input sampling rate.
Pressing the menu button cycles through the functions and when the desired one flashes you can press either one of the two arrow buttons (that also double as previous/next track) to set its value. There are four functions available: Input (USB or Bluetooth), gain (low, medium and high), digital filter (seven options) and output mode (tube or transistor).
The device also has two dedicated volume buttons and the power on/off switch that also wakes or puts the screen to sleep while also locking the buttons. Auto sleep mode is not supported.
Underneath the chassis there are two headphone outputs (3.5mm and 4.4mm), a data USB type-C input and an additional USB type-C power supply port so you can charge and use the device at the same time. The battery charges but it is not entirely bypassed.
Bluetooth performance
The Bluetooth connection is stable and reliable even when you are a few meters away from the device. The sound quality is typical for a modern Bluetooth chipset that supports the high resolution codecs and is only slightly inferior to the wired connection. Nothing weird or different from what is to be expected given Bluetooth’s lossy nature.
Power output and noise
Muse HiFi doesn’t specify the power output of the M5 Ultra which isn’t very powerful given its size. If I was asked to guess, I would estimate around 400-500mW/32Ω because it struggles to drive full sized headphones, except sensitive ones like the Aune SR7000.
Please note that the secondary USB input is only for charging the battery and doesn’t raise power while the 4.4mm headphone output is not really balanced but just a handy adapter.
The M5 Ultra fares very well with sensitive earphones, like the ISN Audio H60, because its background noise is barely audible even in tube mode. The device is surprisingly silent in tube mode and doesn’t produce any microphonic noise even when you tap the chassis with your fingers.
Battery duration
Inside there is a 3000mAh large capacity battery that supports QC4.0 and PD fast charging that gets it charged in about 2 hours. The battery duration depends on various parameters like if you are using tubes or not, and lasted about 8 to 9 hours in tube mode, high gain and USB input.
Listening impressions
Solid-state mode
Starting from the solid-state mode, the M5 Ultra offers stellar sound quality that ideally balances transparency and neutrality with plenty of musicality. Actually, the M5 Ultra is one of the least digital and artificial sounding devices I have tested using the ES9038Q2M DAC chip.
The sound is tonally balanced and neutral with a touch of warmth and a surprisingly good amount of harmonic richness for a device using this particular chip. The bass is full and weighty with strong technical performance and definition. It is fast and tight enough but it doesn’t have class-leading control. It is clear and clean, not hazy or muddy, but it is less precise and focused than the reference ideal. The low-end is a bit loose sounding than strictly disciplined.
The mid-range is admirably expressive and melodic with a natural and realistic timbre. The tuning is neutral and leads to an equally flat treble that is airy and energetic but not bright. It is not rolled-off or subdued, neither lacking in luminosity and resolution, but it is much more smooth and politely expressed than expected from an ESS chip.
Muse HiFi has succeeded in a mature and fatigue-free tuning with minimum digital glare and plenty of natural decay in the higher frequencies, cleverly avoiding any annoying sharpness. The M5 Ultra is far from sounding clinical and boring, it is emotionally engaging and lifelike, not even counting the tube mode.
The soundstage is quite wide, big and immersive enough. Separation and positioning accuracy are very good with all kinds of music, no matter how large or small the ensemble is.
Tube mode
Switching to the tube mode doesn’t make the M5 Ultra too romantic or much less technical and transparent than described above. The tubes are rather conservatively implemented and carefully used to enhance melodic richness without bloating the textures or coloring the sound too much.
The timbre becomes slightly more natural and organic, the mid-range gains in expression, the treble is a bit more relaxed and the bass loses some control in favor of extra elasticity and weight.
The tubes are also beneficial to the soundstage which develops more holographic and atmospheric without renouncing its positioning precision. Details are not smeared out but they are further pushed to the background and blend together with the melody. The tubes make the M5 Ultra even more musical and entertaining without loosing much in definition and fidelity.
Vs the Cayin RU9
The Cayin RU9 ($499) is also a battery-powered, tube-hybrid DAC/amp with both USB and Bluetooth connectivity that is considerably more expensive than the M5 Ultra.
It is equipped with two AK4493SEQ DAC chips and dual 6P1 Nutubes instead of JAN6418. It has a thinner and lighter body than the M5 Ultra but it has a 2000mAh capacity battery that barely lasts 3-4 hours.
The M5 Ultra offers better and stronger Bluetooth reception but the RU9 has an ace under its sleeve. It is much more powerful in battery mode while it supports an external DC mode that raises its power output to desktop levels of 1W*2/32Ω.
The sound of the Cayin RU9 is more technical and precise than the M5 Ultra with some extra clarity and transparency both in solid-state and tube-hybrid modes. In comparison, the M5 Ultra has a bit more analogue-like and organic timbre, its sound is a little more romantic and less modern.
The differences are not that big and ideally I would like to own both as they sound equally good but differently flavored. If I was forced to choose one, I would pick the RU9 for its ability to drive more demanding loads or its portability and the M5 Ultra for its more organic timbre or its extended battery duration and better Bluetooth performance.
In the end
The audio performance of the Muse HiFi M5 Ultra proved much better than expected for the asking price. This is a high quality source that sounds equally good at both solid-state and tube-hybrid modes, offering two distinctive sonic profiles to choose from.
It might not be the most powerful DAC/amp among the competition but it still has plenty of power and great dynamic range while it stands out for its completely noise-free background even in tube mode.
Except for its sound quality, it is also easy to use, well built, visually appealing, and generously accessorized. It would have been an easy recommendation even at its original launch price. But now, at just $195, it’s an absolute steal and the most affordable battery-powered, tube-hybrid DAC/amp on the market. Hurry and grab one while the offer still lasts.
Copyright – Petros Laskis 2025.
+ Stellar audio quality in both modes
+ Minimum digital glare and artificiality
+ Natural and organic timbre
+ Musical and expressive mids
+ Strong technical performance
+ Noise-free background in both modes
+ Wide and immersive soundstage
+ Simple and easy to use
+ Good battery duration
+ Additional USB type-C power input
+ Well made and generously accessorised
+ Great price to performance ratio
- Not very powerful amplifier
- Somewhat heavy and thick
- No SPDIF and line outputs
- The buttons are a little loose
- Bass could be more controlled especially in solid-state mode
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