R-2R DAC vs Sigma-Delta: Which Digital Audio Player (DAP) Sounds Better?

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A Full Discrete R-2R DAC is a type of digital-to-analog converter (DAC) that uses a network of discrete resistors to convert a digital signal into an analog signal. It is called R-2R because it utilizes only two values of resistors-one with resistance R and another with resistance 2R-arranged in a ladder-like structure.

In a Full Discrete R-2R DAC, each resistor is separately implemented using high-precision discrete components rather than integrated circuits (ICs). This gives designers control over resistor quality, matching, and layout, leading to potential improvements in sound quality.


Difference Between Full Discrete R-2R and Other DAC Types

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FeatureFull Discrete R-2R DACIC-Based DAC (Sigma-Delta, Multibit, etc.)
DesignUses discrete resistors and analog switchesUses integrated circuits (ICs) with DSP
Sound CharacterMore natural, analog-like, smooth soundOften detailed but can sound processed
Linearity & AccuracyRequires precise resistor matching for accuracyUses internal digital processing to correct errors
Dynamic Range & NoiseCan achieve high dynamic range if built properlyHigh-end IC DACs have excellent noise performance
Complexity & CostExpensive, difficult to manufactureMore affordable and widely available
UpgradeabilityCan fine-tune components for better performanceIC-based DACs are fixed designs

Advantages of Full Discrete R-2R DACs

  1. Natural Sound – Many audiophiles prefer the smooth and organic sound of R-2R DACs.
  2. No Oversampling or Digital Filtering - Unlike sigma-delta DACs, R-2R DACs can work without oversampling, preserving time-domain accuracy.
  3. Customization & Upgradability - Designers can hand-pick resistors, power supplies, and circuit layouts to optimize sound.

Disadvantages of Full Discrete R-2R DACs

  1. Expensive & Difficult to Manufacture - High precision resistor matching is required to maintain accuracy.
  2. Performance Challenges - Poorly implemented R-2R DACs can suffer from high Total Harmonic Distortion (THD).
  3. Size - Requires more space than integrated DACs.

Digital Audio Players (DAPs) Featuring Full Discrete R-2R DACs

Luxury & Precision P6 Pro

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  • Description: The P6 Pro utilizes a discrete R-2R DAC architecture equivalent to 16 PCM1704K chips, aiming to deliver high-fidelity audio.
  • Features:
    • 3.5-inch touch-sensitive IPS screen
    • 64GB built-in storage with microSD expansion
    • Supports various audio formats, including APE, AAC, ALAC, FLAC, WAV, MP3, WMA, DFF, DSF, AIFF, and SACD-ISO
    • Outputs: 4.4mm balanced and 3.5mm unbalanced
    • Bluetooth 5.0 with LDAC, aptX HD, aptX, AAC, and SBC support
  • Review: Head-Fi Review

HiBy RS6

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  • Description: The RS6 is HiBy's first portable R-2R DAP, featuring their proprietary Darwin audio architecture, which includes a discrete R-2R ladder DAC.
  • Features:
    • Android-based operating system
    • 4.97-inch touchscreen display
    • Dual card slots for expandable storage
    • Multiple output options, including 4.4mm balanced and 3.5mm single-ended
    • Wi-Fi and Bluetooth connectivity
  • Review: SoundNews Review

HiBy RS8

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  • Description: Building upon the RS6, the RS8 is HiBy's flagship DAP featuring an upgraded discrete R-2R DAC design for enhanced audio performance.
  • Features:
    • High-resolution audio support
    • Enhanced internal components compared to the RS6
    • Requires a break-in period of at least 50 to 100 hours for optimal performance
  • Product Information: MusicTeck Product Page

HiBy RS2

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  • Description: The HiBy RS2 is a compact digital audio player featuring a full discrete R-2R DAC with HiBy's proprietary Darwin audio architecture.
  • Features:
    • Darwin Audio Architecture: Discrete R-2R resistor ladder network with linearity compensation, adjustable FIR filter, harmonic controller, and Non-Oversampling (NOS) / Oversampling (OS) modes.
    • HiByOS PureAudio Version: A custom operating system optimized for pure audio playback.
    • Compact Design: 2.45-inch touchscreen, 90.3 x 64.8 x 18.8 mm size, and 158g weight.
    • Dual MicroSD Card Slots: Supports up to 2TB per slot.
    • Multiple Output Options:
      • 3.5mm Single-Ended Phone Output
      • 4.4mm Balanced Phone Output
      • 3.5mm Line Out
    • USB DAC Functionality: Can function as a USB DAC and supports coaxial digital output.
  • Battery Life: 3500mAh battery provides ~10 hours of playback, ~3-hour charge time.
  • Sound Signature: Smooth, organic, spacious, and highly musical.
  • Review: Headfonics Review

Cayin R01 Module for N6ii

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  • Description: The R01 is a discrete R-2R ladder DAC/amp module designed for the Cayin N6ii DAP, offering an alternative to traditional DAC architectures.
  • Features:
    • All-discrete resistor R-2R ladder DAC
    • Compatible with the N6ii DAP, allowing users to switch between different DAC/amp modules
  • Review: Twister6 Review

Conclusion

A Full Discrete R-2R DAC prioritizes natural sound quality and analog smoothness over modern high-precision, high-resolution DAC chip solutions. While IC-based DACs are efficient and cost-effective, Full Discrete R-2R DACs remain a preferred choice for audiophiles seeking a unique, non-digital sonic signature.

These DAPs represent the latest in Full Discrete R-2R technology, catering to those who appreciate high-fidelity, analog-like audio reproduction in a portable form.