CrinEar Protocol Max Portable DAC-Amplifier

I didn’t expect much at first, but after using the Protocol Max for a while, it honestly surprised me. It’s simple, powerful, and just works without any nonsense. For context, I’ve been using the JCALLY JM6 Pro and the FiiO KA13 before this — the JM6 Pro has no real issues but the lack of 4.4mm balanced output limits it, and the KA13 is a bit too warm for my taste and even produces some noise when no sound is playing. The Protocol Max fixes all of that by being clean, quiet, and way more refined overall.

Power-wise, it’s honestly ridiculous for the size. Eco mode handles sensitive IEMs perfectly clean, and Boost mode has no issue pushing headphones or more demanding sets. No hiss, no weird noise floor, no drama — just clean output.

I tested it across my whole IEM lineup — Moondrop Chu 2, LAN, Dusk, Kefine Klean, Truthear Hexa, Truthear Blue 2, and the AFUL Performer 5+2 — and the consistency is what impressed me most.

Chu 2 / LAN / Blue 2
These sets stay dead silent on the Protocol Max — meaning there’s zero background noise when nothing is playing. No hiss, no static, no faint buzzing. Some dongles introduce noise with sensitive IEMs, but here it’s completely clean even at higher volume levels.

Hexa & Klean
Neutral sets stay neutral without losing body. The Protocol Max keeps them clean and controlled without thinning them out.

Dusk
Plenty of headroom, tight bass, and smooth upper mids. No harshness, no compression.

AFUL Performer 5+2
The biggest surprise. The P5+2 can be picky with sources, but the Protocol Max keeps the bass punchy and controlled while keeping the treble clean without harshness. It feels like the dongle gives it proper breathing room without forcing any coloration.

The sound overall is exactly what I want from a source: neutral, controlled, and not trying to “fix” anything. If your IEMs are good, this dongle just gets out of the way.

The PEQ implementation is also way better than I expected. Browser‑based, persistent, and no app nonsense. I set my curve on the Hangout.Audio Graph Tool, saved it, and that’s it — the profile just lives on the device. Only downside is you can store one profile at a time, but honestly, I don’t swap signatures that often.

Build quality is solid, the size is perfect for daily carry, and even the included cable is actually usable — flexible, not stiff or cheap.

If you want a portable DAC/amp that’s powerful, clean, and doesn’t overcomplicate things, Protocol Max is genuinely all you need. It became my daily driver without me even trying.

Pros
Clean, neutral sound with no coloration

Zero hiss even with sensitive IEMs

Strong output power for its size

Eco/Boost modes are genuinely useful

Browser‑based PEQ that actually works well

Solid build and compact form factor

Included cable is flexible and good quality

Consistent performance across all my IEMs

No idle noise or background hiss

Cons
Only one EQ profile can be stored

Slight warmth in Boost mode

Higher price than entry‑level dongles (but performance matches it)

Songs I Tested With
Maggie Lindemann
Hostage — vocal clarity and emotional weight

Different — upper‑mid control and separation

It’s Not Your Fault — checks treble harshness

Ashunite
Amore — sub‑bass rumble and warmth control

Anomaly — imaging, layering, stereo width

Glassworld — micro‑details and background elements

Nessa Barrett
dying on the inside — breathy vocals, noise floor check

VOILA
Therapy — midrange clarity

BEAUTY SLEEP — treble smoothness and sparkle

Drinking With a Cupid — bass punch and rhythm

Figure You Out — layering and overall balance

Chris Grey
Let the World Burn — bass impact and energy

Wrong — vocal layering and mid clarity

Bring Me Back to Life — dynamics and transitions

Burning in Desire — treble sparkle and upper‑mid control

Always Been You — vocal focus

Give Me Your Love — rhythm, bass tightness, separation

Why I Chose These Songs
I picked these songs because they cover pretty much everything I want to test when trying a new DAC. Maggie Lindemann’s tracks help me check vocal clarity and upper‑mid control, while Ashunite’s atmospheric production is great for imaging, layering, and bass texture. Nessa Barrett’s breathy vocals reveal any background hiss instantly. VOILA’s clean mixes are perfect for checking balance, dynamics, and how well the DAC handles brighter treble. And Chris Grey’s tracks bring the energy — they’re great for testing bass impact, transitions, and how the DAC handles modern pop production without getting muddy or harsh. Together, this playlist gives me a solid feel for how the Protocol Max performs across different styles and mixing approaches.

The boost function is powerful enough to run some of the most demanding headphones. It's very nice to have a single quality DAC to run both IEMs and headphones. The PEQ is also great and I like their choice to integrate into Squiglink web app for configuration. My only complaint would be that it is only possible to load one EQ profile at the time, so if you're switching output devices often that might become annoying. Highly recommended!

Also no android support which kind of a let down for the price. Amazing sound out of the box with the Daybreaks of course.

I'm more of a desktop dac/amp kind of person, but I picked this up for portability and convenience, since it measures well and has plenty of power for most of my headphones. I just really wish the PEQ feature was less clunky and annoying. Can only set it up on desktop currently (Windows or Mac, NOT Linux), and disabling it is a chore since you need to manually delete every band you use. I have mine set with a small bass shelf and some treble tweaks and that seems to work well enough for me.

I'll give it 4 stars for now, with 5 coming after PEQ is ironed out for those of us using a portable DAC/amp, y'know, portably.

Otherwise, it sounds good and gets my headphones loud enough to listen to. What more do you want?

I use this together with my phone and work computer. I carry it together with my Crinear daybreak in the daybreak's carry case. Feels like the carry case was designed to be able to hold both.

I haven't had fully time to use the product to be able to fully give a review and to be honest i do not have that many references. I think the build quality is spot on, feels nice, very compact. The accessories supplied with it seems to be of a good quality, very nice USB-C cable, very flexible which means it fits nicely into carry case for Crinear Daybreak.
One nitpick would be maybe about the button functionality, if one presses the volume button a bit too long it seems to run into some bug or loop and you need to disconnect the unit to be able to use it again. As long as use short presses / clicks, no problem. This at least occurs with my phone, google pixel 10 pro xl.