Apos Gremlin Headphone Amp Headphone Tube Amplifier, Class A Balanced Tube review
Quick take
The Apos Gremlin is a compact Class A, fully balanced hybrid headphone tube amplifier built around a preamp tube stage (12AU7 or 6922) and a balanced connection path via XLR and 4.4mm. It’s designed to deliver plenty of output power for many common headphones (8 to 600 ohms), and its tube-rolling flexibility appeals to listeners who like tuning their sound. The main caveat: it’s for headphones only, and you will want a DAC or source that can feed it balanced (XLR or 4.4mm) for the full connectivity design.
Pros and cons
Pros
- Class A headphone amp design with up to 1250 mW output at 32 ohms for strong headphone drive.
- Fully balanced architecture with balanced XLR and balanced 4.4mm I/O.
- Supports replaceable 12AU7/6922 tubes, making tube rolling part of the setup.
- Low measured-noise and high channel-separation figures listed for quiet, detailed listening.
Cons
- Headphone-amp only, not a speaker or guitar amp, and not a preamp.
- Balanced input/output requirements mean you may need compatible balanced cables or a balanced DAC.
- Tube rolling adds an extra variable, so expect some experimentation to land on your preferred sound.
What buyers think
Buyer review evidence points to a few consistent decision-relevant themes: the Gremlin is frequently described as delivering strong sound quality for its cost, with particular praise for warmth and musical midrange character that people associate with tube stages. Several listeners also highlight that it has enough power headroom for demanding headphone types, including planar magnetic models. Setup flexibility shows up too, with buyers mentioning balanced connections and straightforward integration into existing desktop stacks. Buyer-review evidence is limited in detail about long-term reliability or tube lifespan, but overall impressions lean positive on “how it sounds” and “how easily it fits into a balanced setup.”
What is the apos gremlin?
The Apos Gremlin is a Class A, fully balanced hybrid headphone amplifier that uses vacuum tubes in the preamp stage and transistors elsewhere. It’s designed to sit on a desktop system, taking balanced input from a DAC (XLR or 4.4mm) and outputting balanced headphone signals (balanced 4.4mm and 4-pin XLR headphone jacks). The included tube complement is a matched pair of CORE 12AU7 tubes, and the amp is compatible with 12AU7 and 6922 tubes for roll-your-own tuning.
Balanced connectivity that matters for real setups
If your source gear supports it, the Gremlin’s balanced design is a practical advantage. It uses XLR for balanced input and balanced headphone output (via 4-pin XLR), plus balanced 4.4mm connections. In everyday terms, that gives you a cleaner path from DAC to amp and then to your headphones, especially useful when you are building a more “high-end” desktop chain where noise control matters.
Power and headphone compatibility
The amp is specced for a wide headphone range, listed as suitable for headphones with an impedance range of 8 to 600 ohms. It’s also rated for output power up to 1250 mW at 32 ohms, which is the kind of power target that helps with headphones that are harder to drive or that benefit from headroom at higher listening levels. In buyer feedback, this is echoed by people using it with both well-known mainstream headphones and planar magnetic models, describing the pairing as well-matched for drive and overall performance.
Tube rolling and sound tuning (12AU7 and 6922)
The Gremlin’s replaceable tubes support 12AU7 and 6922 types, and it arrives with a matched pair of CORE 12AU7 tubes. Tube rolling is not just about variety, it’s about steering the tonal character of the preamp stage. If you already enjoy swapping tubes to fine-tune warmth, texture, or perceived soundstage, this model’s compatibility range is a strong reason to consider it. If you want a “set it and forget it” amplifier, tube rolling may feel like extra work, but you can still use the included matched tubes right away.
Pros and cons if you’re shopping for a balanced tube headphone amp
It’s a good fit for you if…
- You have (or plan to use) a DAC with balanced XLR or balanced 4.4mm outputs.
- You want a desktop headphone amp that offers both tube-stage character and real power headroom.
- You like adjusting sound through tube rolling, using 12AU7/6922 compatible tubes.
- You’re shopping within a budget where a Class A tube-leaning amplifier with balanced connectivity is a priority.
You may want to look elsewhere if…
- Your source only has unbalanced outputs, because you may not be able to feed the Gremlin the way its fully balanced design expects.
- You need a speaker amp, a guitar amp, or a preamp for other gear, since the Gremlin is headphone-amp only (and is not designed to function as a preamp).
- You prefer to avoid tube-related variables and prefer an amplifier experience that stays totally consistent over time.
Comparison ideas (based on feature priorities)
If you are comparing options, focus less on brand names and more on the decisions that affect your day-to-day listening:
- If balanced connectivity is your priority: the Gremlin stands out with balanced XLR and balanced 4.4mm input/output, which can simplify wiring in a higher-end desktop stack.
- If you need lots of drive power: its stated power rating and broad impedance support (8 to 600 ohms) make it a compelling choice for many headphone types.
- If you want a pure tube experience: a tube-only amplifier may deliver a different flavor of sound, but it can trade off practical factors like output design flexibility. The Gremlin’s hybrid approach aims to combine tube character with stronger output behavior.
Bottom line
The Apos Gremlin is a strong candidate for listeners who want a Class A, balanced desktop tube-leaning headphone amp that can drive a broad range of headphones and supports tube rolling. It looks especially appealing if your DAC and cables are already set up for balanced XLR or balanced 4.4mm, because that lets you use the amp’s fully balanced design as intended. If you need a speaker amp or a preamp function, or you lack balanced-capable source outputs, you’ll likely need a different product category or a differently wired setup.
FAQ
Is the Apos Gremlin a speaker or guitar amplifier?
No. The Gremlin is designed as a headphone amplifier only, not for speakers or guitar use.
Can the Gremlin be used as a pre-amp?
No. It is not intended to function as a preamp.
Does it use balanced inputs only?
It requires balanced connections using XLR or 4.4mm. If your DAC outputs only unbalanced signals, you may need a different connection strategy.
What DAC can I pair with it?
Any DAC with balanced XLR or balanced 4.4mm outputs should be a suitable match.
Can I roll tubes on the Gremlin?
Yes. It supports tube rolling with compatible 12AU7 or 6922 tubes.
Can the Gremlin use 6922 tubes?
Yes. Use compatible tubes as supported by the amp’s tube selection guidance.
Can I turn off the LED lighting under the amp?
Yes, the LED under the Gremlin can be turned on or off.
Can I switch off the orange LED indicators under the tubes?
No, the orange tube LED indicators are not switchable off.
Specifications
| Product Title | Apos Gremlin Headphone Amp Headphone Tube Amplifier,Class A Balanced Tube Amp,Replaceable Tubes 12au7,6922/XLR,4.4mm Balanced Interface.Amp for HiFi Desktop Speakers,Loved By Audio Enthusiasts |
|---|---|
| Category | Electronics > Headphones, Earbuds & Accessories > Amplifiers |
| Brand | Apos |
| Manufacturer | Apos |
| Item Weight | 0.95 Kilograms |
| Warranty Description | 1 Year Manufacturer Warranty |
| Built-In Media | Manual, Power Adapter, Quick Start Guide |
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