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
- Impeccable build quality and craftsmanship, machined from a solid billet of aluminum
- Supreme silence, with exceptionally low background noise, allowing for greater microdynamic detail
- Neutral and uncolored sound, accurately conveying the source material without editorializing, which creates a musically engaging experience
- Excellent linearity, conveying details accurately against black backgrounds—creating a wide and deep soundstage
- The ability to layer performances from front to rear in a wholly convincing manner
- Only balanced XLR connections are available, which may require adapters for systems with RCA connections
Product Considerations
- Lacks adjustable gain and load settings, all settings are predetermined for MM and MC cartridges
- Limited features compared to some competitors, such as multiple inputs or selectable equalization curves
- May not suit Ortofon SPU models and designs such as Audio Note's Io because it needs higher gain
- Compared to the conrad-johnson ET3, lushness and openness were sorely missed, the bass sounded flabby, there was shoutiness to the vocals, and an overall lack of atmosphere and spaciousness to the sound
Comparisons (according to reviewers)
- The 508 is a big step down in performance compared to Boulder 2108
- The PS Audio was preferred in handling of drums and bass, and was more natural with vocals
- The Boulder 508 offered across-the-board improvements in sound quality compared to the Parasound Halo JC 3 Jr
- The Boulder 508 has a more natural presentation, where the Anatek MC1 is slightly harder on sibilants
- Pass Labs XP-27 provides upper frequencies with more amplitude
Takeaway: The Boulder 508 is a well-built and neutral-sounding phono stage that is easy to set up, which is good for audiophiles that prefer a simple system or are just starting with vinyl. Its quiet operation and detailed sound make it a good choice for experiencing all the detail that vinyl has to offer.
All
508
reviews

Manufacturer details
- Inputs: 1 pair balanced, converts to unbalanced
- Outputs: 1 pair balanced
- Input Impedance: MC: 100 ohms, MM: 47k ohms
- Output Impedance: 100 ohms, balanced
- 1 kHz Gain, RIAA: MC: 70 dB, MM: 44 dB
- Frequency Response, RIAA: ±0.5 dB, 20 Hz to 20 kHz
- Distortion, THD: 0.01%
- Noise (EIN), MC: 116 nanovolts flat, 20 Hz to 20 kHz
- Maximum Output Level: 16 Vrms
- Crosstalk: >100 dB or better 20 Hz to 20 kHz
- Weight: 11.5 lbs. (5.2 kg)
- Power Requirements: 100, 120, 200-240 VAC, 50-60 Hz
- Power Consumption: 15W maximum
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:
- Boulder prioritizes a "straight wire with gain" philosophy, focusing on neutrality and avoiding any specific sonic signature, allowing the source material to dictate the sound.
- The brand is known for a distinct industrial design, often featuring topographical contours and heatsinks that are considered aesthetically pleasing.
- They are committed to building all components in-house, including metalwork and circuit boards, to maintain exceptional quality control and durability, resulting in products with high secondary market value.
- Boulder's products are designed for long-term use and reliability, withstanding daily use and long periods of being left on with excellent circuit protection, although power consumption can be high.
Select products
Boulder 861
- Positioning: The entry-level model in Boulder's lineup, designed for smaller spaces and efficient systems.
- Description: Offers a compact design with 75W peak power per channel, making it ideal for small rooms or setups where space is limited.
Boulder 1161
- Positioning: A mid-range option, offering a balance between size and power for those who need more than the 861 but less than the 1160.
- Description: Delivers 200W peak power per channel. It shares the same operational features as the larger 1160 but in a more manageable size.
Boulder 1160
- Positioning: A high-performance model in the 1100 series, offering significant power and advanced features.
- Description: With 300W per channel, it features improved thermal management and a new grounding system, setting it apart from the 1161 by offering greater power and clarity.
Boulder 2160
- Positioning: A premium model in the 2100 series, offering top-tier performance and power.
- Description: Provides 600W per channel, making it one of Boulder's most powerful amplifiers. It features a fully-balanced design and advanced thermal management, surpassing the 1160 in power and performance.
Boulder 3060
- Positioning: The flagship model, representing the pinnacle of Boulder's amplifier technology.
- Description: Delivering 900W per channel, the 3060 is designed for the ultimate audio experience, with unmatched power and precision. It features a pure Class A operation and extensive use of Boulder's highest performing gain stages.
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Used
Boulder
What if you spend more?
Product Strengths
- Offers a versatile range of adjustments, including nine input impedance choices and four gain options, to match various cartridges
- Offers three different equalization curves (RIAA, Decca London, and American Columbia), unusual for phono stages in its price range
- Produces a clean, smooth, lucid, and well-balanced sound that is uncolored and neutral, allowing for greater transparency and speed
- Musical, smooth, coherent and dynamic, with a very good pace, rhythm, and timing
- Touchscreen interface is easy and intuitive to use
Product Considerations
- Moving magnet capacitance is set at 220pF and is not adjustable
- Some reviewers express concern about potential RF interference from the digital display affecting the analog circuitry, particularly with sensitive MC cartridges
- Instrumental images may be smaller than with other phono stages
- May sound a little weightless compared to significantly more expensive phono preamps
- Reviewers note the forthcoming PSU-5 power supply
Comparisons (according to reviewers)
- Compared to a similarly priced phono stage, the Gold Note PH-5 provided greater insights into how Miles Davis played each note, and was more full-bodied and dynamic
- The Pathos In the Groove was more spacious and shapely sounding but lacked the PH-5's sense of control and smoothness
- Compared to the Gold Note PH-10, there's a remarkably similar sound, with a tad more weight to recordings played through the more expensive PH-10
- The PH-5 sounds closer to the GrandiNote Celio MK IV—a bit richer, smoother, and more saturated—whereas the ESE Lab Nibiru is more about speed, precision, and transparency
Takeaway: The Gold Note PH-5 is a versatile phono stage that sounds musical and natural. It provides many options to adjust the sound, and it is an affordable way to get great performance from vinyl records.
Video review
Our take on the brand
Product Strengths
- Straightforward, high-quality preamp that does everything asked of it, very well
- Includes tone control knobs for bass and treble to personalize the listening experience
- Allows turntable users to switch between moving magnet (MM) and moving coil (MC) modes
- Features seven source audio inputs, a front-panel 3.5mm headphone jack, Bluetooth 5.1, optical and USB inputs, as well as a phono stage for turntables
Product Considerations
- Bluetooth 5.1 connectivity, while present, is not super high resolution compared with Wi-Fi and may not appeal to those seeking a more robust streaming experience
- Has no balanced inputs
Comparisons (according to reviewers)
- Against Rotel's RC-1572 MKII, the Adcom GFP-915 wins in many audiophile categories, such as a lower reported total harmonic distortion and noise floor
- The Schiit Freya S stereo preamp at $599 is another solid, no-frills audiophile option that can compare to the Adcom GFP-915
- The NAD C 3050 integrated amp's HDMI switching, internal DAC, Bluetooth 5.4 and phono stage might sway one to spend a few hundred more dollars than the Adcom
Takeaway: The Adcom GFP-915 is a traditional stereo preamp that delivers quality performance and offers a range of useful features for audiophiles. It is a worthwhile option for those seeking a simple and effective way to manage audio sources and volume control.
Video review
Our take on the brand
Product Strengths
- Features a fully discreet headphone amplifier built-in that sounds good
- Offers flexibility with passive, low gain, and high gain settings, not commonly found at its price point
- Build quality feels good, with a nice textured black finish
- Features a precise 128-step attenuator for accurate left-right balance, unusual for a $699 preamplifier
- Features a metal remote with volume, mute, and input selection
Product Considerations
- One reviewer experienced the Kara going into protection mode and muting the sound when adjusting the volume quickly—requiring a power cycle to resolve
- One reviewer said they prefer the RCA input and output sound
- XLR inputs for stereo mode are not available
Comparisons (according to reviewers)
- Vs Schiit Freya S: It replaces the Freya S and has significant upgrades, including a headphone jack and a more powerful power transformer
- Vs Pass Labs HPA1: The Pass Labs is a better-sounding pre-amplifier and headphone amplifier overall, but is significantly more expensive
Takeaway: The Kara preamplifier offers great flexibility with gain options and a good-sounding headphone amplifier. It's a well-built component that could be a good addition to an audio setup, especially if clarity is valued.
Video review
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Our summary
Product Strengths
- Balanced connections improve sound, though stellar audio is available via RCA inputs
- Tighter and continuous control over load impedance via a potentiometer control
- Discrete circuit design offers a more neutral sound than integrated circuits
- Two turntables can be connected at once, one with XLRs and one with RCAs
- Expanded soundstage and individual instrument placement both horizontally and vertically
Product Considerations
- Turntable with XLR outputs needed to experience its best features
- More expensive if balanced connection features are not being used
- Tube box will push coloration into the mix, so tubes need careful system matching
- Balanced outputs and moving coil cartridge are needed to reveal the sort of detail that vinyl aficionados champion
Comparisons (according to reviewers)
- Vs NAD Phono Preamp PP-1: Allows for markedly more detail and separation between instruments
- Vs Phono Box S3 B: Integrates all the technology from the SB3 and adds in a few extra features, as well as a potentiometer
- Vs Projects Tubebox DS3: The sound is far more clear, and the weighted treble and upper spectrum sound more pronounced
Takeaway: The Pro-Ject Phono Box DS3 B unlocks the potential of a turntable, enhancing the listening experience with more dynamics, details, and soundstage. It's a versatile phono preamp with remarkably neutral and detailed sound.
Video review
Our take on the brand
What competes at this price?
Our Summary
Product Strengths
- Good sound quality, warm with lows and highs present, and a quiet noise floor
- Supports both Moving Magnet (MM) and Moving Coil (MC) cartridges
- Adjustable gain settings to match different cartridge output levels
- Metal construction for durability and shielding
- Offers DIY upgradeability with a socketed op-amp that can be swapped to change the sound signature
Product Considerations
- The ground post is positioned close to the power input, which can be inconvenient
- To power it off, one must press and hold the power button instead of pressing it quickly to turn it on, which is not intuitive
- Lacks a headphone jack
- Does not have a subsonic filter or capacitive loading switch
Comparisons (according to reviewers)
- Compared to the Schiit Audio phono preamp, the Fosi Audio Box X5 is on par or better than the Schiit Audio phono preamp generation one version
Takeaway: The Fosi Audio Box X5 is a great value phono preamp that provides good sound quality and versatile features for both MM and MC cartridges. It is a solid choice for anyone looking to upgrade from a built-in preamp or start with their first turntable.
Video review
Our take on the brand
Our Summary
Product Strengths
- A very low noise floor, even with high gain settings for moving coil cartridges
- Various gain settings for moving magnet and moving coil cartridges, making it versatile
- An 'intelligent' subsonic filter effectively reduces rumble without negatively impacting bass frequencies
- A balanced 4.4mm output, which is uncommon in phono stages at this price point
- Impressive sound quality for its price, including a wide soundstage and good dynamics
Product Considerations
- Large diameter RCA plugs may not fit due to the small chassis
- The number of load settings is stated inconsistently across sources, with some stating four and others stating three
- Connecting RCA and balance output together simultaneously to two different amplifiers can result in noticeable humming noise
- One reviewer mentioned a 'clinical' sound that might pair better with warmer cartridges, though this was addressed by changing the setup
Comparisons (according to reviewers)
- The ZEN Phono 3 has a wider soundstage and better dynamics than the iFi Zenfone Stage
- The ZEN Phono 3 has deeper bass than the Accuphase AD-60, but slightly less clarity and definition in the bass region
- The ZEN Phono 3 delivers a larger, beefier—and more rhythmic sound than the built-in phono stage in the U-Turn Orbit Special
- The ZEN Phono 3 produces significantly less noise than the Musical Fidelity M5SI phono stage
Takeaway: The ZEN Phono 3 is a valuable phono stage that provides a clean and dynamic sound, along with features typically found in more expensive units. It is especially useful for those looking to upgrade from a basic phono stage or for vinyl enthusiasts who want to explore different cartridge types.
Video review
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Our Summary
Product Strengths
- Offers a full feature set including balanced XLR inputs and outputs, typically found in more expensive units
- Provides remote control functionality for adjusting gain, loading, and filters from the listening position
- Delivers detailed, clean, and modern sound reproduction, with good transient clarity and precision, and quiet backgrounds
- Offers versatile settings for both Moving Magnet (MM) and Moving Coil (MC) cartridges
- Improves system sound, adding clarity and a warmer feel compared to budget options
Product Considerations
- Some users experienced a static or buzzing noise in the left channel, with inconsistent severity
- The initial balanced input tests revealed D.C. issues, causing speaker drivers to alarmingly suck in and out
- The unit's physical aesthetics are not particularly eye-popping or luxurious
- The tiny silkscreened letters and icons associated with the front panel LEDs might be difficult to read
- May not be ideal for systems already on the lean side, as it might not add warmth
Comparisons (according to reviewers)
- Vs Schiit Manny, the Skoll is much quieter
- Vs Michael Yee PFE1, the Skoll has less hum and more hiss
- Vs Fosi Audio Box X4, the Skoll has better clarity
Takeaway: The Schiit Skoll is a versatile and feature-rich phono preamp that delivers impressive sound quality and customization options. It can be a great upgrade to get more enjoyment out of vinyl records.
Video review
Our take on the brand
Our Summary
Product Strengths
- True balanced connections reduce noise and increase detail, dynamics, and musicality
- Settings are easily adjustable on the front panel, including impedance, capacitance, and gain
- Well-made metal chassis is compatible with both MM and MC cartridges
- Discrete circuits are used in its gain stages, which Pro-Ject believes delivers the best sound
- Offers both single-ended (RCA) and balanced (XLR) inputs and outputs
Product Considerations
- Balanced cables are required for optimal performance if using balanced connections
- Relay switching causes a time lag when switching impedance, capacitance, or gain
Comparisons (according to reviewers)
- The Lehmannaudio Black Cube had more power in the low end, while the Pro-Ject tended toward a drier character
Takeaway: The Phono Box S3 B is a well-designed phono stage offering balanced connections, making it a great choice for those wanting to upgrade their vinyl listening experience. The adjustable settings and solid build quality make it a versatile and worthwhile addition to any system.
Video review
Our take on the brand
Our Summary
Product Strengths
- Cohesive, lively, and musical performance
- Expressive dynamics and good insight
- Strong rhythmic drive
- Quality of build and finish is perfectly fine for the money
- Adds some warmth to the sound, along with vitality—with the right cartridge
Product Considerations
- Only cosmetic changes over the previous generation
- Only compatible with moving magnet cartridges
- Treble could be a bit sweeter
- The review mentioned a feel of a cheap Chinese amp, and the power button feeling cheap
- Matching well with the right cartridge is critical to get the best sound
Takeaway: The Rega Fono MM Mk5 offers a strong and engaging performance for the price, making music sound lively and fun. It's a great choice if one wants to enhance their vinyl listening experience with a moving magnet cartridge.
Video review
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