Overview

The 3e Audio A5 is a finished Class D stereo amplifier built around two TI TPA3251 chips in PBTL with a post-filter feedback (PFFB) loop. It offers RCA and balanced XLR/6.35 mm combo inputs, user-replaceable op-amps, volume-bypass mode, and auto signal sensing. The unit ships with a 38 V/5 A PSU and is specified for 2–16 Ω speakers (balanced input mode).

Scientific Validity

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Third-party tests show the A5 delivers approximately 121 W into 4 Ω at 0.1% THD+N (both channels, XLR input). THD+N vs power curves dip below −100 dB at typical listening levels, with 1 kHz FFTs around −100 dB at 1 W and about −104 dB at 5 W. Output impedance/damping is high enough to keep FR essentially flat, and the frequency response is ~20 Hz–35 kHz within ±0.5 dB (balanced mode). The design is stable down to 2 Ω loads per documentation. Collectively, these data indicate transparent amplification under normal use. [1][2][3]

Technology Level

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This is a careful, modern implementation of TI’s TPA3251 with post-filter feedback, swappable op-amps, balanced inputs, and volume-bypass. While the core silicon is mainstream, 3e’s execution (PFFB tuning, layout, features) reflects competent engineering rather than novel topology. [1][2][4]

Cost-Performance

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No cheaper finished amplifier was found that simultaneously offers balanced inputs and matches or exceeds the A5’s measured performance (≈121 W into 4 Ω at 0.1% THD+N and sub-100 dB THD+N minima).
Near-miss cheaper options:

• Topping PA5 II Plus (balanced TRS) measures ~102 W into 4 Ω at 0.1% THD+N—~16% lower power, so it does not meet the A5’s performance criterion. [5]
• Fosi ZA3 (balanced/XLR-TRS) publishes ~89 dB SINAD (manufacturer figure), which is below the −100 dB-class distortion demonstrated by the A5 at low power. [6]

Given the A5 street price of 240 USD (with PSU) and the absence of a cheaper equal-or-better alternative, CP = 1.0. [3]

Reliability & Support

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The official user manual states a 1-year warranty. As a small manufacturer, 3e Audio’s long-term service network remains modest, but the simple Class D architecture and documented specs (including auto on/off and protection) are reassuring. [1]

Rationality of Design Philosophy

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The A5’s choices—balanced inputs, PFFB, high damping, volume bypass, and socketed op-amps—are all performance-oriented and verifiably beneficial. Independent measurements corroborate the intended outcomes (low distortion/noise, linear FR). [1][2][3]

Advice

If you specifically need balanced inputs and want transparent, ~120 W-class stereo power into 4 Ω with lab-verified low distortion, the A5 is outstanding value. If balanced I/O or the −100 dB-class distortion target is not essential, cheaper amps exist—but they will fall short on at least one of these metrics.

References

[1] 3e Audio, “A5/A7/A7 Mono User Manual (2024-11)”, https://www.3e-audio.com/wp-content/uploads/2024/11/A5_A7_A7-Mono-User-Manual_202411.pdf (accessed Aug 2025). Key points: inputs incl. XLR/TRS & RCA; FR ±0.5 dB to ~35 kHz; 2–16 Ω support (balanced); warranty 1 year.
[2] Archimago’s Musings, “Part I: 3e Audio – A5 Stereo and A7 Mono… Features and initial measurements.” Nov 30 2024, https://archimago.blogspot.com/2024/11/part-i-3e-audio-a5-stereo-and-a7-mono.html
[3] Archimago’s Musings, “Part II: 3e Audio – A5 Stereo and A7 Mono… power, distortion, and the subjective.” Dec 11 2024, https://archimago.blogspot.com/2024/12/part-ii-3e-audio-a5-stereo-and-a7-mono.html (A5 ≈121 W @0.1% THD+N, THD+N minima < −100 dB; A5 price ~240 USD noted).
[4] 3e Audio, “A5x A7x Series – Next-Gen PFFB Amplifier”, Aug 16 2024, https://www.3e-audio.com/finished-amp/a5x-a7x-series/
[5] Archimago’s Musings, “Part II: Topping PA5 Mk II Plus (PA5II+) Class D amplifier – power & distortion.” Oct 28 2023, https://archimago.blogspot.com/2023/10/part-ii-topping-pa5-mk-ii-plus-pa5ii.html (≈102 W @0.1% THD+N into 4 Ω).
[6] Fosi Audio, “ZA3 Balanced Stereo Amplifier” (manufacturer specs incl. SINAD 89 dB), https://fosiaudio.com/products/fosi-audio-za3-balanced-dual-mode-class-d-amplifier (accessed Aug 2025).
[7] Benchmark Media Systems, “AHB2 Power Amplifier” (price reference 3,499 USD), https://benchmarkmedia.com/products/benchmark-ahb2-power-amplifier (accessed Aug 2025).

(2025.8.25)