Note that this is a discontinued product. You may want to visit the brand's page here to browse their newer products.
What reviewers think
Bloggers and YouTubers have tried this product—so we've summarized their strongest opinions below. Links to full reviews follow.
Product Strengths
- Highly adaptable sound signature through NOAH modules and vocal switches, enabling four distinct tuning profiles
- Excellent treble delivers clarity without sibilance or fatigue
- Technically excels in imaging precision and creates an immersive, three-dimensional soundstage that positions instruments with remarkable specificity
- One review stated that it is one of those sets that can do it all
Product Considerations
- Large shell size may challenge those with smaller ears
- Demands power-hungry sources, often requiring high-gain amplification to reach full potential
- Tip selection is very important to the fit, the shells are fairly big and flat, and the design makes the tips a make-or-break element of the fit
- Switch placement may be an issue, the vocal switch is positioned in such a way that the switch can be easily activated when inserting or removing the IEM
- Can sound a little sharp for some when using the blue module
Comparisons (according to reviewers)
- Vs. Custom Art Omnium: Somewhat equally performing IEMs, Grand Maestro is bassier and has a wider soundstage
- Vs. Empire Ears ETOILE: Grand Maestro Anniversary is more engaging, the GMA has more of a clear W-shaped tuning, and the GMA wins on imaging
Takeaway: The GRAND Maestro Custom IEM is a versatile IEM with customizable tuning options, allowing users to tailor the sound to their preferences and different music genres. Its excellent technical capabilities, particularly in imaging and soundstage, create an immersive listening experience.
All
GRAND Maestro Custom IEM
reviews

Manufacturer details
- Drivers: Tribrid system — Dynamic driver + Balanced Armature drivers + Electrostatic drivers
- Crossover: Multi-way passive crossover
- Frequency Response: 20 Hz – 40 kHz
- Connector: 2-pin connector
- Fit Type: Custom in-ear monitor
- Linear Impedance: Proprietary impedance correction ensures consistent frequency response across playback devices
- Sonar La Trompa™: Horn-inspired acoustic curvature improves treble tonality and gain control
- PhaseAlign: Acoustic delay structures align low, mid, and high frequencies for coherent arrival at the eardrum
Brand highlights
Taking a step back to look at reviewers' thoughts of the brand's entire lineup—not just this product—what stands out most is the following:
- FATfreq is recognized for its distinct "basshead" sound signature, delivering powerful and impactful bass responses, particularly in the sub-bass region, without sacrificing clarity in the mids and highs.
- They offer customizable sound profiles through interchangeable NOAH modules and tuning switches, allowing users to tailor the IEM's sound to their preferences.
- FATfreq IEMs often feature high driver counts and tribrid configurations, combining dynamic drivers, balanced armatures, and electrostatic tweeters to achieve a detailed and balanced sound.
Select products
Reference Pro SE Universals
- Positioning: A compact, studio-grade IEM reimagined with enhanced vocal clarity.
- Description: Offers an extra tweeter designed to bring out vocal transparency and detailed transient response in a balanced tonal presentation. Compared to the Musician Pro and Quantum models, it emphasizes clean studio reproduction over extended bass or planar dynamics, making it ideal for users focused on vocal performance and moderate budgets.
Musician Pro SE Universals
- Positioning: A bass-optimized IEM tuned for energetic performance and low-end impact.
- Description: Offers a uniquely tuned three-way crossover with an extra low-frequency driver that deepens bass without bleeding into mid registers. In comparison to the Reference Pro SE, it prioritizes vigorous bass output, while Quantum and flagship models deliver additional precision and modular control.
FATfreq x Effect Audio: Quantum
- Positioning: A high-performance IEM featuring innovative planar driver and modular tuning technology.
- Description: Offers a planar magnetic driver paired with detachable Noah modules and a premium Ares S II cable to ensure speed, accuracy, and fatigue-free clarity. Unlike the Reference and Musician models that focus on one tonal aspect, it provides enhanced customizability and balanced resolution.
Hayabusa Universals
- Positioning: A versatile flagship IEM designed for both live and studio applications with dual tuning options.
- Description: Offers dual-mode tuning via an analog bass toggle and incorporates additional super tweeter modules to enhance vocal detail and instrumental separation. Compared to the entry-level Reference and Musician series, it bridges the gap with creative tuning flexibility, while remaining more accessible than the ultra-premium Grand Maestro.
GRAND Maestro Universals
- Positioning: The ultimate high-end monitor featuring state-of-the-art customization and advanced acoustic technology.
- Description: Offers customizable NOAH modules, precisely engineered bass chambers, and a built-in vocal boost switch to deliver exceptional detail and tailored frequency response. In contrast to all other models in the lineup, it delivers superior build quality, expansive soundstage, and cutting-edge technology.
Our take on the brand
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Used
FATfreq
What if you spend more?
Product Strengths
- Build quality is sensational, handmade in Taiwan, and has thousands of man hours put into it
- The kit has detachable clickable connections, and high-quality pure copper cables
- Comes with accessories such as replacement parts for the earbuds, and adapters (3.5, 4.4 for balance, and 2.5 balance)
- Accessories are beautifully made with wood and good hinges
- The product features a two-way speaker system inside an earbud
Product Considerations
- It demands good, abundant power to be driven, due to its specifications of 93dB sensitivity, and 182 Ohms
- Needs to be burned-in (driven) for no less than 200 hours, and most possibly 300 hours
- The stock cable has tiny connectors which make it very difficult to connect any wire beyond 26-28awg
- The outer packaging box seems to be a reformed cardboard box, which is huge and white, and may not be durable in the long run
- The proprietary MMCX-designed connectors means the cable’s tiny connectors make it very difficult to connect any wire beyond 26-28awg and perhaps a very thin 2 or 4 wire at best
Comparisons (according to reviewers)
- The oBravo RA-C-CU excels versus the Vision Ears EVE2020 across every parameter, though there is a warmth across the EVE’s midrange via its dynamic driver, that moves it to, at least, competitive with the RA-C-CU and its Neodymium Dynamic Driver
- There were no aspects between the Vision Ears ELYSIUM and the oBravo RA-C-CU where the oBravo did not excel
- The oBravo RA-C-CU extends a competitive advantage across all relevant parameters from bass extension to treble extension to transparency to a coherency that holds together through the most complex and dynamic passages to a more expansive soundstage, compared to the oBravo EAMT-2C
Takeaway: The Ra-c-cu (21.5) is a very well-made earbud that gives a sensational listening experience like high-end speakers in one's ears. If one wants to treat oneself with serious earbuds where money is not a problem, this is the way to go.
Video review
Our take on the brand
Our summary
Product Strengths
- Considered by many as having the best sound achievable in an in-ear headphone, making it an exceptional audio experience
- The sound signature is mostly balanced with tasteful coloration, where the treble imparts a particular element that is potentially preferable
- The midrange is extremely well done
- Features unique SLAM subwoofer, woofer, midwoofer, mid tweeter, tweeter and EST technologies
- Built with Grade 5 titanium, providing sturdiness and high quality
Product Considerations
- Treble performance can be hit or miss depending on the listener's anatomy and HRTF
- Requires more power than typical IEMs, potentially draining the battery of portable audio players
- Shells are on the larger side
- The included cable is nice, but the chin cinch tends to slide down
Comparisons (according to reviewers)
- Compared to the Hi-Senior Megafest and Dusk Default DSP, the Storm is an editorialized or enhanced version of those IEMs, particularly regarding bass and mids
- Compared to the 64 Audio U6T, it has similar balance with similar tasteful colorations, but Storm's bass is more punchy and the upper treble is more to the reviewer's preference
- Compared to the Empire Ears Odin, the Storm is preferred because the Odin is not as versatile, and the Storm sounds more detailed
- Compared to the Empire Ears Raven, the Storm is more normal in a good way because the Raven has massive bass and a strange lower midrange resonance feature
- Resolution, stage and tonality are better on the Storm compared to Grand Maestro
Takeaway: The Storm is a high-end IEM with exceptional sound quality and great build, even if pricey. It could be worth buying for those who want the best possible audio experience and appreciate a balanced sound with unique features.
Video review
Our take on the brand
Video review
Our take on the brand
Product Strengths
- Fuller body smooth analog tonality and a neutrally balanced sound signature
- Naturally resolving treble
- Expanded soundstage
- Beautiful, exotic material shells and premium leather accessories
- Very light weight
Product Considerations
- The high price is a significant consideration
- Performance is source pair-up dependent
- The included PWA First Times Shielding Pro cable has some microphonics
- Shells are a little bigger in comparison to previous Mason FS models and MM/AP models from Mentor-series
Comparisons (according to reviewers)
- Vs Unique Melody Amber Pearl, the Soleil Tombé has less bass and is more neutral, allowing for clearer mids compared to the Amber Pearl's stronger bass presence
- Vs U12T, the Mason FS has better bass impact and texture, while the Mason FS also presents vocals as warmer and fuller, with more atmosphere, while the U12T presents a very clean and clear sound, though it is less energetic
- Vs Noble Onyx, the Mason FS is warmer, while the Onyx has a larger, more open sound, though the Onyx can be clearer in higher registers but loses clarity in lower registers compared to Mason FS
- Vs UM Mason FS Le Jardin (LJ), the 2024 model is just $499 more
Takeaway: The Mason FS Soleil Tombé is a very good-looking IEM that provides a unique listening experience with balanced sound and beautiful mids. It is for people that want something different than other products in the market.
Video review
Our take on the brand
What competes at this price?
Our Summary
Product Strengths
- Offers four distinct tuning profiles through its NOAH modules and vocal switches, ranging from bass-forward to mid-centric.
- The treble, managed by electrostatic drivers, delivers clarity without sibilance or fatigue.
- Excels in imaging precision and creates an immersive, three-dimensional soundstage with remarkable instrument placement.
- The 'Grand Origin' cable included with the Anniversary Edition uses a mix of copper, silver, gold and palladium that looks and sounds incredible.
- The bass is textured, warm, and has an organic quality that is lush and very musical.
Product Considerations
- Large shell size may challenge those with smaller ears.
- Demands power-hungry sources, often requiring high-gain amplification to reach full potential.
- The position of the vocal switch makes it easy to accidentally toggle it.
- To unlock all four possible tunings, the second NOAH module must be purchased separately.
- The shells are fairly big and flat, and the design makes the tips a 'make or break' element of the fit.
Comparisons (according to reviewers)
- The GRAND Maestro Universals are bassier than the Aroma Audio Jewels, but the Jewels have a slight edge in midrange, GRAND Maestro Universals have better imaging and wider soundstage, while the Jewels are more resolving.
- GRAND Maestro Universals have more versatile tuning profile options than the Flipears Aurora XXIV.
- The Volk Audio ETOILE has a more reserved, reference-like tuning, while the GRAND Maestro Anniversary has a clear W-shaped tuning.
Takeaway: The GRAND Maestro Universals offer very customizable sound through its module system and switch, and it images well with a fantastic soundstage. This is a top-tier IEM that could be worth the money if you enjoy its unique design.
Video review
Our take on the brand
Our Summary
Product Strengths
- Excellent technical performance and detail retrieval, considered several cuts above other IEMs
- Outstanding imaging performance, with precise soundstage and instrument separation
- The bass response is a highlight, delivering a punchy sub-bass with texture and articulation
- Offers a warmer tonal balance that is easy to get into with a mostly 'neutral' sound
- Bone conduction enhances low-frequency extension, reverb, and detail
Product Considerations
- Large chassis that may be uncomfortable for some users, particularly those with smaller ears
- The subdued treble range may not provide enough energy and sparkle for some listeners
- Stock cable is lackluster in terms of usability due to its plasticky feel, rigidity, and microphonic feedback
- Driver flex (a harmless crinkling sound upon insertion) is present
Comparisons (according to reviewers)
- Legend Evo delivers a stronger bass impact, depth, and extension than the Legend X
- Legend Evo produces better constructed highs than the Legend X
- Legend Evo shows better clarity than the Legend X, and has more detail
- The Legend X can sound veiled concerning the Legend Evo
- The Legend Evo feels a touch smoother than the Empire Ears ODIN
Takeaway: The Legend Evo is a top-tier IEM with innovative bone conduction technology that creates a unique and immersive listening experience with enhanced bass. It is a great option for those seeking flagship-level performance with a warm, bass-focused sound signature.
Video review
Our take on the brand
Our Summary
Product Strengths
- Excellent detail retrieval, resolving with the best over-ear headphones, challenging the brain to take it all in.
- Wide soundstage with precise imaging, creating an immersive, holographic 3D image.
- Easy to drive, delivering speed and impact even with low-power sources.
- High level of craftsmanship and build quality, using premium materials like CNC-machined aluminum and Damascus steel faceplates.
- Comes with the Magnus cable, a high-quality 8-core cable constructed with graphene, monocrystalline silver, and copper-silver alloy.
Product Considerations
- Treble can become a bit hot and fatiguing over long periods, but can be mitigated by using foam ear tips.
- Bass presence is more nominal and cohesive, not dominant or overpowering like some bass-head IEMs.
- Fit may be an issue for some due to the larger-than-average size of the IEM.
- Could be fatiguing over time due to sensory overload from extreme detail.
- Some reviewers found that the upper mids/lower treble frequency range could use a little boost.
Comparisons (according to reviewers)
- Offers a stronger balance of detail, performance, and musicality, a fuller, richer midrange, and better texture and timbre, when compared to the Empire Ears Odin—Odin has stronger holographic separation, an intense sense of vocal performance, and more potential for fatigue.
Takeaway: The Noble Viking Ragnar is a top-tier IEM, offering incredible detail and a wide soundstage for an immersive listening experience. Its build quality and design are exceptional, making it a great choice for those who want some of the best IEMs in the market.
Video review
Our take on the brand
Our Summary
Product Strengths
- Tremendous transparency, offering a wealth of microdynamics and spatial cues, critical in determining positioning and layering.
- Incredibly clear sound, yet wrapped in a warm, lush, and inviting overall picture.
- Highs are extended, detailed, and wonderfully resolved, easily able to summon the ethereal or holographic when called for.
- The soundstage is quite impressive—deep, wide, with very good headroom, and holographic when called to be so.
- The shell design is comfortable with a short nozzle, and light weight.
Product Considerations
- The treble is a little bit relaxed, and some songs may not cut through the way they need to.
- Amplifiers for this particular headphone are going to matter, and they are going to make a difference between several different amplifiers.
- The bass does not bring the rumble, nor the impact, nor does it reach to the stygian depths of the Holy-Bass-Head-Grail.
- Though the Odin provides for a comfortable fit, it can be uncomfortable for people who have really small ear holes, as the stem itself is quite wide.
- The 'Bifröst' faceplate design might be too flashy for some.
Comparisons (according to reviewers)
- Vs Empire Ears Zeus: The Odin smashes the Zeus all day, every day, for sound quality, with a better midrange and significantly nixed highs.
- Vs 64 Audio U12T: Odin is at least as good, if not better, in the mids and the bass, and has better punch and slam to the bass frequencies.
- Vs Empire Ears Legend X: The Odin is a much more balanced-tuned IEM.
- Vs 64 Audio Tia Forte: The Odin has a more agreeable frequency response.
- Vs Thieaudio Monarch: The Monarch has a really nice bass shelf, but the Odin has better technical performance and a better frequency response.
Takeaway: The Empire Ears Odin offers an easygoing listening experience and clear sound, and has tight bass response with a great midrange. It could be a great choice for those seeking a warm IEM with finesse.
Video review
Our take on the brand
Our Summary
Product Strengths
- Incredibly clear and detailed sound, offering a transparent window into the music
- Well-defined, punchy, and high-quality bass response, with good impact and rumble, without being muddy
- Smooth and well-defined treble, avoiding sibilance or harshness, and retaining excellent resolution
- Broad and deep soundstage with excellent imaging, layering, and separation of instruments
- Visually striking and beautiful Bifrost faceplate design
Product Considerations
- The fit may be uncomfortable for users with smaller ears, as the stem is quite wide and the monitors themselves are fairly large
- Upper mid-range can be forward, and at times can be borderline shouty or fatiguing in some tracks
- Treble response, while detailed, might be a little relaxed for some, not cutting through as much as some other IEMs
- Some reviewers found the build quality of the resin shell to be just okay, not feeling particularly premium or durable relative to the price
Comparisons (according to reviewers)
- Vs. 64 Audio U12T: The Odin has better punch and slam in the bass, while the U12T has a more layered and separated sound with slightly more micro-details
- Vs. Empire Ears Legend X: The Odin is much more balanced and refined compared to the bass-heavy Legend X
- Vs. Fir M5: The M5 has a more forward and clearer treble response and wider soundstage, but the Odin's midrange is more forward and produces a more enjoyable vocal response
- Vs. Empire Ears Zeus: The Odin is smoother with more bass response and a better mid range
- Vs. Vision Ears Elysium: The Elysium brings an analog-like ease to the midrange, but is not a match for the Odin in detail and transient speed
Takeaway: The Empire Ears Odin is a technically impressive IEM with a smooth, clear sound, detailed bass and a striking design. If one is seeking a high-end listening experience where details are clearly displayed in an immersive 3D stage, these could be a great match.
Video review
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