The Audio Stuff - Amplifiers Reviews

HIFIMAN Serenade Review: One Box to Replace Your DAC, Amp, and Streamer

Jakub Charkiewicz — Sun, 14 Jun 2026 00:00:00 GMT

HIFIMAN's all-in-one R2R DAC, discrete Class A amp, and hi-res network streamer in one 3kg box - lush, musical, and powerful enough to drive almost anything.

Verdict: Reference - 9.3/10. Price: $999.

What's good

Proprietary Himalaya Pro R2R DAC for a natural, non-clinical sound
Discrete Class A amp based on HIFIMAN's $3000 Prelude
Built-in hi-res network streamer (up to 32-bit/768kHz, DSD512)
Massive, ultra-clean power supply (50W toroidal + 30,000µF)
4W into 32Ω balanced - drives 99% of headphones with headroom
Every input and output you'd need: USB, optical, coax, Ethernet, Bluetooth, RCA
Beautifully built ~3kg block of CNC-machined aluminum
Dead-silent noise floor (THD 0.0015%, SNR 110dB)

Worth knowing

Voiced warm and lush on purpose - not for fans of a bright, clinical sound
Class A circuitry runs warm by design
If you already own a similar-tier amp, the pricier Prelude is the smarter buy

Read the full HIFIMAN Serenade review on The Audio Stuff

Denafrips Hades 12th Review: The R2R Preamp That Changes Things

Jakub Charkiewicz — Tue, 12 Aug 2025 00:00:00 GMT

A pure Class A, fully balanced, true discrete preamp with a 60-step relay-based resistor ladder volume control - perfect channel balance, 0.00045% THD, 122dB SNR.

Verdict: Highly Recommended - 9.0/10. Price: $1,369.

What's good

Precision-machined thick aluminum chassis, no flex
60-step relay-based stepped attenuator (R2R volume)
Perfect channel balance at any volume
Pure Class A, fully discrete, true balanced signal path
80VA O-core transformer with discrete linear PSU
0.00045% THD, 122dB SNR - whisper-quiet background
Solid aluminum remote that matches the build
Adjustable display brightness for any room

Worth knowing

Three feet instead of four - could be more stable
Unity gain only - some amps may need more volume
9kg unit isn't trivial to move around
Simple I/O - just 2 XLR + 1 RCA in, XLR + RCA out
Display can't be fully turned off
Relay clicks may bother those who want silent volume changes

Read the full Denafrips Hades 12th review on The Audio Stuff

Tonewinner AD-1PA+ Review: A $4,000 Class A/AB Beast

Jakub Charkiewicz — Mon, 14 Jul 2025 00:00:00 GMT

A 43kg switchable Class A/AB power amplifier paired with a fully balanced preamp - 100W Class A or 500W Class AB into 4Ω with serious bass control and golden-hued mids.

Verdict: Highly Recommended - 9.0/10. Price: $3,999.

What's good

Massive 43kg overbuilt chassis with side heatsinks
Switchable Class A / Class AB topology
Fully balanced differential input and BTL output stages
8 pairs of Hi-Fi transistors per channel - 60A capacity
1200W toroidal transformer + 180,000μF capacitance
Stable down to 2Ω - drives demanding speakers
Matching AD-1PRE+ preamp with built-in phono stage
Tactile, milled-metal volume knob with notched rotation

Worth knowing

Significant heat output in Class A mode
Class AB sounds drier and more clinical vs Class A
Notes start/stop more abruptly - lacks tube fluidity
43kg is hard to move - placement is permanent
Up to 1200W power draw from the wall
No automatic Class A/AB switching

Read the full Tonewinner AD-1PA+ review on The Audio Stuff

HIFIMAN EF500 Review: The Cheapest Himalaya R2R Ever

Jakub Charkiewicz — Tue, 03 Jun 2025 00:00:00 GMT

The most affordable HIFIMAN unit to feature their proprietary Himalaya R2R DAC chip - 4.5W per channel balanced, network streaming, and a vertical tower form factor.

Verdict: Recommended - 8.2/10. Price: $549.

What's good

First Himalaya R2R DAC chip at this price point
Vertical tower form factor saves desk space
All-metal chassis with industrial design
Fully balanced amp section - 4.5W into 32Ω balanced
Network streaming via Ethernet (Tidal, Qobuz, NAS)
OS/NOS filter selection for tonal tailoring
117dB SNR, <0.0025% THD
131dB channel separation

Worth knowing

Gets warm during long sessions with demanding cans
Vertical-only design - awkward laid flat
No analog input - can't use as a separate amp
Soundstage is solid but not ultra-wide
Filter differences are subtle
Pricier than the EF499 with overlapping feature set

Read the full HIFIMAN EF500 review on The Audio Stuff

HIFIMAN EF499 Review: A Real R2R DAC/Amp Under $300

Jakub Charkiewicz — Sun, 09 Feb 2025 00:00:00 GMT

A balanced R2R DAC/headphone amp with built-in network streaming for under $300 - warm, musical, and a serious one-box answer to the separates-or-not question.

Verdict: Recommended - 8.1/10. Price: $299.

What's good

All-metal chassis, no QC issues - HIFIMAN's build has matured
Smooth, precise volume pot with virtually no wobble
Doubles as a vertical headphone stand
Built-in network streamer - Tidal, Qobuz, NAS
Philips R2R chip with NOS/OS selector
Balanced output: 4.35W per channel into 32Ω
Fully balanced DAC and headphone amp
Lush, natural midrange with deep, controlled bass

Worth knowing

No analog input - can't use as a standalone amp
Soundstage is well-defined but not the widest
Layering could be slightly more refined
Primarily designed for vertical placement
Not the typical HIFIMAN Himalaya R2R architecture
THD+N of 0.008% isn't a measurement chart-topper

Read the full HIFIMAN EF499 review on The Audio Stuff

Tonewinner AD-2PRO+ Review: Heavy and Powerful Class A/AB Integrated Amp

Jakub Charkiewicz — Mon, 08 Apr 2024 00:00:00 GMT

A 40 kg, 240W integrated amp with switchable Class A and Class A/B modes, neutral tonality, and the kind of dynamic headroom that pairs well with virtually any speaker.

Verdict: Highly Recommended - 8.8/10. Price: $2,699.

What's good

Massive 40 kg / 80 lb solid build with large heatsinks
Switchable Class A and Class A/B operation
240W into 8Ω, handles speakers below 4Ω with ease
Neutral tonality with rich, full-bodied midrange
Exceptional instrument separation
Built-in DAC with USB DSD512 / PCM 32-bit/768kHz support
MM/MC phono, sub-outs, two pairs of speaker outs
Easy-to-read front LED screen

Worth knowing

Center image can be a little fuzzy
Soundstage favors width over pinpoint imaging
Generates a lot of heat over time
Heavy and large - placement requires planning
THD below 0.05% isn't extremely low for the price

Read the full Tonewinner AD-2PRO+ review on The Audio Stuff

HIFIMAN EF400 Review: Entry-Level R2R DAC + Class AB Amp Combo

Jakub Charkiewicz — Sun, 18 Feb 2024 00:00:00 GMT

An entry-level Class AB amp/DAC with HIFIMAN's Himalaya R2R DAC, fun subjective sound, and a slightly soft character - underpowered for the hardest planar loads.

Verdict: Recommended - 7.5/10. Price: $399.

What's good

Himalaya R2R DAC with NOS / oversampling option
Full balanced output - 4-channel mode
Beautifully built, all-aluminum chassis (~3 kg)
USB Type-C input alongside USB Type-B
Single-ended (1/4", 3.5mm) and balanced (4.4mm, XLR4) headphone outs
Pairs perfectly with most HIFIMAN headphones
Full and rich sound, typical of class A/AB designs

Worth knowing

Specced 4.4W, but independently measured closer to 3W into 32Ω
Modest objective measurements (THD+N 0.002-0.004%)
Not enough power for HE6se, Susvara, or Modhouse Tungsten
Slight wobble in the volume knob
Channel imbalance in the first 10% of volume - tricky for IEMs
Sounds a bit shouty with very raw vocals

Read the full HIFIMAN EF400 review on The Audio Stuff