Sonic Compass · Mojo Review · Amplifier (headphone) · Session Review
Eufonika H5 KPCU
A handmade Polish OTL tube amp with solid-state speed and detail, and a holographic stage. Brilliant on 100 to 600 ohm headphones, wrong for IEMs.
An absurdly good-value tube amp for high-impedance headphones. It pairs a modern solid-state amp's speed and linearity with holographic tube staging. Don't put a low-ohm planar on it.
- Holographic stage with height
- Solid-state speed and detail on tubes
- Fast, punchy, controlled bass for an OTL
- Dead-silent noise floor
- Handmade and bespoke at about two-thirds of an Echo Vibe
Where it sits
Sonic Compass does not score gear out of ten. Gear and listeners are plotted on the same seven axes, so a review tells you where a product sits — and you can see how far that is from where you sit. A position is a description, not a grade.
- Tone ColourWarm · 62%
- Texture DetailVery detailed · 86%
- Dynamics JumpVery punchy · 82%
- Space & ImagingVery spacious · 92%
- Timing & FlowVery rhythmic · 86%
- Comfort & FatigueVery easy-going · 80%
- Emotional EngagementVery immersive · 82%
Only a little warm (high = warm on this scale). A trace of second-order tube harmonics, with no dark vintage filter and no roll-off up top.
Resolution is next level for a tube amp, with micro detail picked out easily and the treble extended. Close to the Echo Vibe, and a hair more detail up top.
Fast, punchy, tightly controlled bass that goes deep on the Verite, with a chest-thumping beat and no distortion at high level.
Wide, diffuse and holographic, with height. The standout. The Apollo chatter on Daido sits in each ear and the rain sits outside the head.
Solid-state speed and attack on tubes. Transients are quick and clean on both the techno and the acoustic tracks.
Zero sibilance and a dead-silent noise floor. Not bloated or syrupy, so I could listen loud without distortion.
Vibrant and punchy, with vocals that carry weight and body, and a stage that wraps around me. The techno tracks are made for it.
Sonic Compass does not grade gear. We plot gear and listeners on the same seven axes, so a review tells you where a product sits and you can see how far that is from where you sit.
Four years ago I asked the maker to build me an amp for low-impedance planars, and he built me a hybrid I still use. He has since sold direct, and offered to make an OTL for my channel if I paid postage, about US$110 from Poland to Australia. He sent two amps, a hybrid H5 and this H5 KPCU. I have posted on his Headfire thread for four years. He did not see this review or have any say in it.
I used the Crescendo Verse DAC into an Aurelic LP20 streamer, with ZMF Verite and Sivga SV023 (both 300 ohm) and an unreleased 32 ohm dynamic pair. I have not tube rolled it yet.
Listening journey
Daido, Arya (Armin van Buuren, Universal Religion mix) (trance / techno) — Real Apollo 7 NASA chatter in each ear and rain outside. Staging and placement are excellent. The beat is clean, snappy and fast, the synth bass deep with real weight, and on the Verite the bass drops about 3dB further. Zero distortion, zero sibilance, even at a dangerous level.
Witchwoman (AI version) (rock) — Very clean, resolving and snappy, with great bass depth. The AI vocals and band sound plastic, but I could hear every detail.
Sweet Dream Fanfare, Jethro Tull (prog rock) — A real sense of surround sound, pushed further in every direction than on solid state. You can just hear the faintest second-order tube harmonics. Horns and high synth notes hang around me like stars.
Morph the Cat, Donald Fagen (jazz / pop) — The bass run reaches sub-bass. Vocals are natural and well placed. Trumpets and guitars sit left and right in a sphere, and the hi-hat reverb is clean and fast.
Winter (club remix), Vivaldi (classical / techno) — Like sitting beside a sub at a rave. The bass is low and well controlled and I can feel it in my skull. The synth is crisp and sparkly.
Aerials, System of a Down (metal) — Deep, well-controlled bass and rich, organic vocals.
| Track | Position | Note |
|---|---|---|
| Daido | 94% | Superb staging, clean snappy beat, deep synth bass |
| Witchwoman | 82% | Clean and resolving, though the AI vocals sound plastic |
| Sweet Dream Fanfare | 92% | Surround-sound spread with a hint of tube harmonics |
| Morph the Cat | 92% | Natural vocals, sub-bass depth, sonic sphere |
| Winter (club remix) | 94% | Sub-like bass, tightly controlled, sparkly synth |
| Aerials | 88% | Deep, controlled bass and rich vocals |
Critical observations
Where the H5 KPCU sits — Fast, clean and holographic, with a faint second-order tube glow. Space, Texture and Timing are its strongest axes. It gives ground on power (about 300mW) and inputs (one).
Bass — Fast, punchy and tightly controlled, not the flab OTL amps can suffer. On the Verite it goes deeper still.
Mids and treble — Vocals have weight and body and stay natural. The upper registers don't roll off: no dark vintage filter, just clear extension.
Stage and imaging — Wide, diffuse and holographic, with height. The standout.
Noise floor — Dead silent, with no transformer hum, helped by a heavily filtered CLC choke-regulated supply.
The KPCU capacitors — The H5 is a respectable amp as standard. The KPCU option swaps the signal-path capacitors for Miflex KPCU copper-foil paper-in-oil types, so large the maker deepened the chassis to fit them. The reason they sound as they do is the maker's claim and my research, not my own test against the standard H5.
H5 KPCU vs Feliks Echo Vibe (about US$1,200) — Extremely similar. The H5 has a hair more detail up top; the Vibe presents vocals a fraction more forward, has a tad more power (pot at about 11 o'clock against about 130) and three inputs against one. Imaging and bass are neck and neck. The Vibe ran from a different DAC, so the comparison isn't fully controlled. I love both, and the H5 costs about two-thirds as much.
Read this against your own profile — I like fast transients, a wide holographic stage and plenty of detail, with 300 ohm headphones already on hand. If you want solid-state speed with tube staging and own 100 to 600 ohm headphones, this fits. If you use IEMs or low-impedance planars, or want a thick syrupy tube sound, it doesn't.
Honest limits — Supplied by the maker, with postage paid by me. Stock tubes only. The Echo Vibe comparison used a different DAC and was by ear, with no measurements. Low-impedance behaviour is by the maker's description, not my testing.
- DaidoArya
- Sweet Dream FanfareJethro Tull
- Morph the CatDonald Fagen
- Winter (club remix)Vivaldi
- AerialsSystem of a Down
- Driver Configuration
- OTL (output-transformerless) tube headphone amplifier
- Driver Details
- 6N8S (or 6SN7) driver tube, 6N13S output tube, Miflex KPCU copper-foil paper-in-oil capacitors, Alps potentiometer
- Impedance
- Suited to 100 to 600 ohm headphones
- Build Materials
- Handmade; metal chassis deepened to fit the large capacitors; colour chosen by the buyer (reviewed unit dark reddy-brown)
- Cable Connectors
- One input; can also be used as a preamp
- Power Requirements
- About 300mW output; CLC choke-regulated power supply
- Build Quality Notes
- About US$815 with the KPCU capacitors and tubes, per the reviewer. Handmade in Poland by Eufonika.
An absurdly good-value tube amp for high-impedance headphones. It pairs a modern solid-state amp's speed and linearity with holographic tube staging. Don't put a low-ohm planar on it.
<p><strong>Buy it if</strong>… you own 100 to 600 ohm headphones; you want holographic staging with solid-state resolution; you love handmade gear; or you want Echo Vibe-level sound for about two-thirds of the price.</p><p><strong>Skip it if</strong>… you mainly use IEMs or low-impedance planars; you need several inputs; or you want a thick, warm, syrupy tube sound.</p><p>Until next time: peace, and stay metal.</p>