The Pocket HiFi Era Powerful Single-Ended & EA4 Synergy LO — 4 Ways the AD1955 Card for E7 Stands Out
Following the highly acclaimed E7 AK4497 Signature Edition, which pushed the AK4497 chip to its limits, the E7 now welcomes its latest interchangeable module—the very first card to be sold separately. This new module features two legendary ADI flagship DAC chips: the AD1955. It also marks the first time in nearly two decades that this iconic ADI chip has been applied in a portable HiFi device.
As ADI’s crown jewel, fully unleashing the potential of the AD1955 while crafting a tuning style distinctly different from the AK4497 edition posed the greatest challenge in developing this new E7 module. After several rounds of internal testing and tuning based on feedback from audiophile beta testers, the final version delivers four key standout features:
1. A Distinctive Sense of Refinement
With dual AD1955 chips and their debut in a portable player, we set out to deliver the pure essence of the "1955 sound" to on-the-go users. During the Shanghai Headphone Expo in early March, the E7 prototype paired with the AD1955 module received unanimous praise. Listeners described the sound as crystal-clear, refined, and uniquely elegant. Staying true to that impression, we’ve preserved the AD1955’s signature sophisticated tone, infusing a touch of Hi-End DAC tuning into a portable DAP.
2. A Powerful Single-Ended Output
Last year’s LP5 10th Anniversary Edition was praised by some users as having “the strongest single-ended output,” though many never got to hear it due to its limited release. This time, the E7 AD1955 card delivers a significantly enhanced single-ended output that rivals the balanced one. Unlike typical designs that only utilize “half the circuit” for single-ended output (saving power at the expense of performance), this AD1955 card enables all four output channels from the two DAC chips, along with IV conversion, LPF, volume control, and buffer stages to operate in full. This means E7 delivers the same dynamic performance from its single-ended output as it does from its balanced port—bringing the full “1955 sound” with no compromises, regardless of which connector your headphones use.
3. Synergistic LO Designed for EA4
The E7’s Line Out has been specially optimized for use with the EA4 amp. When first introduced with the P6P 10th Anniversary Edition, the EA4-exclusive LO enhancement received widespread acclaim. So, with the AD1955 card, we’ve brought this feature back. Five years ago, the E7 AK4497 card was designed when EA4 was still in development. Now, with the EA4 architecture fully matured, the AD1955 card integrates the same LO enhancements seen in the limited anniversary edition—creating a dream-team combo of the E7 and EA4.
4. Consistent Sound with Smart Bias Compensation
This card features a custom-designed, fully discrete automatic bias compensation circuit to maintain consistent sound across various settings. Built around a network of transistors, MOSFETs, and resistors, the circuit automatically adjusts the DAC reference current and IV stage bias voltage according to the playback configuration. This allows the AD1955’s natural tonal characteristics to shine through consistently and accurately.
Important Notes:
Current E7 users should immediately update to the latest firmware released this week. The update resolves several system issues and is necessary for supporting the AD1955 module and its additional functions. Please contact customer support or authorized dealers to obtain the new firmware.
More details on the AD1955 module’s circuitry and tuning philosophy will be shared in upcoming articles—stay tuned!
