Sierra Referencia

Amazing balance and extension. Beautiful, airy highs, and no hint if harshness. The headphones are very comfortable for extended listening sessions. I like the industrial, rugged looks too. Excellent product for the price!

As a huge fan of detail-rich productions à la Trevor Horn, the vibrant sound design of Yello, and all kinds of electronic and techno styles, I’ve absolutely fallen for the Sierra. Its transient response is stunningly quick, the sub-bass reaches deep without getting bloated, and the mids and highs feel airy—never harsh. It doesn’t just reveal what is in a recording but also how it's being presented—exactly what I look for as an audiophile. The passive filter design acts like an acoustic polish: clarity meets musicality. The Sierra isn’t some neutral observer—it’s a charismatic storyteller. And that’s precisely why I love it.

What also won me over is the thoughtful design—minimalist, premium, and free of anything unnecessary. Every detail feels built with longevity and function in mind. As for comfort? I often forget I’m even wearing the Sierra. Even after extended listening sessions, there's no pressure, no heat buildup, no need for adjustment—just pure sound. For me, that’s about as close to perfection as it gets.

I'm more of an IEM guy and don't really listen to music with headphones these days, especially not open-back ones, as it seemed like the best ones were just way outside of my price range. Regardless of all that, the idea of the AA Sierra Open Monitors intrigued me, and initially I kept my expectations measured, and simply wanted to support a small, independent, audio equipment maker. Especially one that made their products in America. But man, I was truly blown away by the quality of these when I finally got the chance to listen with them properly.

The sound quality is top-notch, and even though that's always subjective and a matter of personal taste, I truly do think you get your money's worth with this one. The lows, middles, and bass all sound great with none of them being too overpowering or sounding muddy. But songs still feel exciting when you listen to them, not a super boring sterile sound like you get with more hard neutral sound signature headphones.

All in all, I love these and I wish nothing but the best and more continued success for the folks at Auribus Acoustics!

For starters - what an experience buying these headphones, I was reached out to by Juan himself to let me know he would be in my state for a period of time and thus it was possible to have them hand delivered, Juan you rock!

The title of the review speaks for itself, absolutely remarkable headphones, what has been achieved here is for me at least? endgame potential - this is the first pair of open backs that I feel need no EQ whatsoever, they are perfectly balanced right out of the box.

The bass is absolutely the star of these given they are an open back Dynamic driver, perfect Harman like bass and the treble extension is just perfect. Not, harsh, sibilant or shouty, just the right amount of sparkle and resolution.

With that said the only thing I would mention is the build quality is very sturdy, but you can tell these are not mass produced. The 3D printed material has an interesting feel to it, maybe the one thing I could see improved is the swivel on the cups? This is nit-picking of course because frankly Juan has achieved something so incredibly impressive.

They are incredibly comfortable. More so than the Sennheiser HD 650 and those are regarded as some of the most comfortable headphones, the weight is just perfect too, not too light that it feels cheap and not too heavy that it's a neck workout just to wear them.

The soundstage is impressive too! As far as I am concerned these are the Sennheiser HD 600 / 650 upgrade that everyone has been clamouring for.

I seriously look forward to what Auribus Acoustics does in the future, should these headphones ever become produced on a larger scale with better build materials I would buy it again I love them that much, amazing product, could not recommend enough!!!!

Big fan of Sennheiser, was previously using the HD800s with a bass shelf and have had the HD600 for a decade. One song with the Sierra was enough to move it to the #1 slot. Mostly listen to jazz (Rippingtons, Arc De Soleil, Checkfield) and electronic (Hello Meteor, Duett, EPSON, Perturbator)