The Gremlin tube amp is a compact headphone amplifier made by Apos Audio that challenges the assumption that tube warmth requires either massive footprints or massive budgets. At around $120 including matched tubes, it sits in a space where most competitors offer either soulless solid-state performance or expensive vintage gear that generates enough heat to warm a small room.
Key Takeaways
- The Gremlin tube amp costs around $120 with matched Ray Core 12AU7 tubes included.
- Class A hybrid design uses tubes for preamp duties and solid-state op-amps for the output stage.
- Delivers 1250mW at 32Ω, enough to drive sensitive IEMs and full-size 600-ohm headphones.
- Fully balanced architecture (XLR or 4.4mm Pentaconn) with no single-ended outputs.
- Open-frame design with visible internals emphasizes signal path transparency and aesthetic appeal.
Why the Gremlin Tube Amp Stands Out
The Gremlin tube amp succeeds because it rejects the black-box aesthetic that dominates affordable audio. Instead of hiding its internals behind plastic, this device uses clear Lexan plates on top and bottom with stainless steel standoffs, making the signal path from input to output visually traceable. At just 5 inches wide, 3.25 inches deep, and 2.5 inches tall, it occupies far less desk real estate than traditional tube amps while maintaining the sonic character audiophiles chase.
The design philosophy matters here. Apos Audio developed the Gremlin in collaboration with its community and reviewers, explicitly targeting the gap between generic budget amps and five-figure reference equipment. The result feels intentional rather than compromised. A Head-Fi reviewer captured this precisely: after listening to the Gremlin, they found it hard to justify hauling out a much more expensive Eddie Current Zana Deux tube amp, noting they get most of the performance with a smaller footprint and significantly less heat.
Gremlin Tube Amp Sound Character and Architecture
The Gremlin tube amp uses a Class A hybrid amplifier topology where tubes handle preamp duties while solid-state op-amps manage the output stage. This split approach yields low output impedance—critical for driving a wide range of headphones—while preserving the warmth and harmonic coloration that makes tubes appealing in the first place. The amp runs in Class A, meaning it maintains constant current flow regardless of signal level, which reduces distortion and delivers every note with consistent purity.
Sound-wise, the Gremlin tube amp delivers warm, euphonic character without the syrupy veil that plagues cheap tube amps. Users report articulate deep bass, detailed treble with a three-dimensional splashy quality, and an intimate soundstage that feels like a club rather than a stadium. Importantly, volume changes do not alter the sound signature, meaning the warmth stays consistent whether you are listening at whisper levels or pushing the amp harder. The included matched pair of Ray Core 12AU7 tubes set the tonal character, but the design supports tube rolling with any 12AU7 or 6922 tubes for those who want to experiment.
Gremlin Tube Amp Connectivity and Power Specifications
The Gremlin tube amp is fully balanced from input to output, accepting XLR or 4.4mm Pentaconn inputs with matching outputs. This is a strength for balanced headphone systems but a limitation if you own single-ended IEMs or headphones—there are no single-ended outputs, so balanced gear is a requirement. The amp delivers 1250mW at 32Ω, enough to drive sensitive IEMs to their limits or power full-size 600-ohm headphones quietly and powerfully.
For a desktop setup, the Gremlin tube amp pairs naturally with balanced sources like DAPs (digital audio players) with 4.4mm outputs or audio interfaces with XLR outputs. This requirement for balanced connectivity is not unusual at the audiophile level, but it does mean you cannot simply plug in any headphone amp and expect it to work.
How the Gremlin Tube Amp Compares to Alternatives
The most direct comparison is to the Eddie Current Zana Deux, a tube amp that costs significantly more and generates substantial heat. The Zana Deux creates a massive soundstage like a stadium, whereas the Gremlin offers an intimate club-like staging. For most listeners, the Gremlin’s smaller footprint and cooler operation make it the practical choice, even if the Zana Deux reaches further into the soundstage dimension.
Against other cheap tube amps, the Gremlin tube amp stands apart. Budget tube amplifiers typically produce gooey, thick, bassy sound that muddies detail. The Gremlin avoids this trap by maintaining clarity and euphonic character without the syrupy veil. Compared to high-end solid-state amps like the Pietus, the Gremlin cannot match flat, neutral performance, but it is the stronger entry-level tube option for listeners who prioritize warmth and character over reference accuracy.
Is the Gremlin Tube Amp Worth Buying?
At $120, the Gremlin tube amp represents genuine value for headphone listeners who want to experience tube sound without committing to expensive vintage gear or boutique pricing. The open-frame design, Class A architecture, and included matched tubes make it a complete package out of the box. The main constraint is the balanced-only connectivity—if you own single-ended headphones or IEMs, you will need to adapt or upgrade.
The Gremlin tube amp excels for desktop listeners with balanced headphones who want warmth and character without aesthetic compromise. It is not a reference monitor for mixing or mastering, nor is it designed to be. It is a personality-filled amplifier that makes listening to music feel intentional rather than utilitarian.
What tube rolling options does the Gremlin tube amp support?
The Gremlin tube amp ships with a matched pair of Ray Core 12AU7 tubes, but it supports any 12AU7 or 6922 tubes for rolling. Tube rolling lets you shift the sonic character—different tubes can emphasize warmth, detail, or frequency balance. This flexibility is rare at this price point and appeals to listeners who want to personalize their sound.
Does the Gremlin tube amp require balanced headphones?
Yes. The Gremlin tube amp has no single-ended outputs, only XLR and 4.4mm Pentaconn balanced outputs. You will need balanced headphones or IEMs to use it. If you own single-ended gear, you will need to either upgrade your headphones or look for an alternative amplifier.
How much heat does the Gremlin tube amp generate?
The Gremlin tube amp runs in Class A, which means it consumes more power than Class AB or Class D designs. However, reviewers note it generates significantly less heat than larger tube amps like the Eddie Current Zana Deux, making it suitable for desktop use without ventilation concerns. The compact form factor and hybrid design keep thermal output manageable.
The Gremlin tube amp fills a real gap in the audio market: it proves that affordable tube warmth does not require compromise on design, transparency, or sound quality. For balanced headphone listeners tired of generic black boxes, it is a compelling entry point into the world of tube amplification.
Where to Buy
$80 FiiO KA13 | Schiit Vali 3 ($189) | Topping L30 II ($149)
Edited by the All Things Geek team.
Source: Creativebloq
