Tony Ware We may earn revenue from the products available on this page and participate in affiliate programs. Learn more › Tullamore, County Offaly, sits 22km from the geographical center of Ireland. That’s not quite right for a survey marker, but still a Midlands milestone if you’re judging by heart not GPS. Whiskey fans may know the town from a bottle; it shares its name with the Tullamore D.E.W. distillery. But it’s just another exit off the motorway for many travelers. However, for all intents and purposes, for my intents and purposes, it’s the hub of sights and especially sounds that define my short time in Ireland. I’m here at the invitation of Sennheiser—one of the most recognizable brands in audiophile audio, now celebrating its 80th anniversary. And if you’re into headphones, which I am, you’ll find something in the reclaimed bogs even more intoxicating than alcohol.  Here, on the outskirts of this modest community quietly humming just over an hour west of Dublin, sits the Sennheiser factory and Audiophile Experience Center (AEC). Here, icons are assembled, and we assembled—journalists from multiple countries and multiple channels here to observe automation and human interaction produce some of the most lauded personal audio accessories of the last 30 years. Here, it’s not about chasing trends; it’s about chasing truth. Here originate headphones, including the HD 600, HD 650, HD 800 S—pilgrimage points for anyone obsessed with signal paths and sonic signatures. If you know a guy on a forum with a handle like “DACDaddy76,” he wants to be here. So, here are my thoughts on seeing what goes into reference-grade products, what it’s like to build a pair of headphones. And how it feels to hear the HE 1 electrostatic system—the world’s most expensive critical-listening cans. Before we get to the production line, a brief timeline. Fritz Sennheiser founded his namesake company in a farmhouse outside of Hanover, Germany, in 1945. It wasn’t until 1968 that Sennheiser added a headphone, the HD 414 with its iconic lemon-yellow foam pads, to the company’s microphones and other professional recording and broadcasting products. However, this pivotal move set the stage—and soundstage—for decades with its pioneering open-back (“Open Aire”) design.  In 1991, Tullamore joined the Teutonic team. The facility started making transducers (the full-range speakers inside headphones) that would define the HD 580 Precision in 1993 and HD 580 Jubilee in 1995—known for their warm but balanced voicing. These were followed by 1997’s HD 600, which became the quintessential Sennheiser headphone due to its resolving yet not fatiguing nature. With a reliable build and natural voice, it’s a headphone that loves to show off its source during long listening sessions.  In 2003, the HD 650 was introduced, with a sound favoring thicker over quicker. In 2009, the HD 800 became Sennheiser’s flagship—a benchmark of forensic clarity at a then-costly $1,399 (so quaint considering prices nowadays … even the current 800 S revision is more at $1,799). Throughout these product launches and more, product management team members remained in Wedemark, DE, so the Tullamore factory would fabricate the drivers and then ship them to Germany for final assembly.  In 2021, Sennheiser’s consumer portfolio was acquired by Swiss hearing care solutions company Sonova Holding AG. Sennheiser transducers had long been manufactured in Tullamore, and, within a year, assembly and packaging of the 600 Series and 800 Series, as well as additional lines, moved there to streamline and optimize production. In 2023, the Tullamore facility renovated its lobby to create an exclusive enclave where select guests can listen to headphones produced there. That brings us up to date. That brings us up to a gate. To one side of the AEC lobby, Sennheiser proudly displays a wall of finished products, from highly portable in-ear monitors to top-tier headphones, from affordable to aspirational. But how to construct these conduits for transparent playback still resides behind opaque doors. Packed full of dozens of proprietary machines doing upwards of 80 processes, it’s a recording device-free zone.  Pat Fulton is the Willy Wonka for our peek behind the secure entranceway (and, yes, golden tickets are used as invitations). Fulton, seen above, is plant manager and has been at the facility for over 30 years. He’s been there as Tullamore has expanded its systems and manpower. He’s there as we walk under pneumatic conveyors and past plasma nozzles to audio inception.  The first step to a Sennheiser headphone begins here, with the selection of which material and mould will contribute to the acoustical performance of the transducer. In the model we monitor, a 0.03mm wire is adhered to the membrane, that bond kept within surgical tolerances thinner than a strand of hair. Then it’s off to the next to the next workstation. It’s kinetic but not chaotic.  Between each strand binding, every composite bonding, any electromechanical adjustment, the diaphragm’s oscillation is tested to ensure each ripple behaves obediently across the entire surface and sound spectrum. It doesn’t matter whether it’s the 7mm TrueResponse transducer in the IE 900 or the 56mm Ring Radiator in the HD 820; QC is a non-negotiable.  It’s complex routing with a flexible flow; Fulton says the line is adaptable and scalable, if need be. Just give the factory an hour and a checklist. That’s good, because Sennheiser has been quite active adding SKUs and seasoning to its lineup in 2025. Since I went to Ireland, the company has introduced two new mid-range models: the HD 505 Copper and HD 550. The latter, in particular, is a new mainstay for articulate, budget-conscious fidelity. Automation, while invaluable, hasn’t fully replaced manual assemblage, however. Once transducers are off the belt, they’re finessed by teams from the plant’s 100-plus skilled employees—some here since the 600 Series launch, some fresh out of technical college. This mix of callouses and newcomers ensures tribal knowledge isn’t just preserved, it’s evolving. Which is good because there’s more to tuning than just the curvature of an embossed foil. There’s positioning the baffle, the resonators, the ear pads, how other components and casings are coupled. And ensuring the necessary attention to detail requires a balance of precision and passion. The 800 Series, in particular, requires exacting interaction, with dedicated, specially trained technicians specially trained in its architecture. After seeing that elite pod, we’re given a hands-on opportunity, but at a lower tier. Our simpler, solder-free task: Piece together an HD 660S2—a model introduced in 2023.  Parts are laid out under fluorescent lights, a quick demonstration is given, and then it’s our turn to cycle through the steps. Mesh grilles are pushed on the driver chassis, foam cushions clipped in place, ear cups snapped to the headband, detachable cables plugged in. There’s a cadence to the sequence that a robot might be able to follow. But the satisfying physical feedback confirming completion might be harder for machinery to register.  Finally, the headphones are popped into an anechoic chamber for frequency sweeps to verify everything’s aligned and operating within razor-thin margins of error. Once validated, our builds are bagged and boxed, complete with Made in Ireland certification and serial number stickers in case any faults need to be traced to a batch or, gulp, builder.  Our shift complete, we’re led beyond the manufacturing maze to our last showcase. Partitioned behind glass is Damian, the artisan responsible for the 3,000 parts and hundreds of hours that go into each HE 1—the $70,000 bespoke headphone system. Want one? Sennheiser requires you put down a $10,000 deposit and prepare to wait up to 45 days, assuming component availability and Damian’s bandwidth allow (four were simultaneously in production during our visit). Once they’re ready, you pay the remainder. But what you get for your five-figure investment is a testament to transcendence. What goes into the HE 1 is improbable, impractical, and awe-inspiring. It’s a middle finger to compromise. It’s not just a headphone; it’s a moonshot. Beyond mystique, the HE 1 is a block of Italian Carrara marble, selected for both its aesthetics and vibration-damping properties. Within this spring-loaded structure are all manner of routing options—S/PDIF, optical, USB, unbalanced RCA, and balanced XLR.  Whatever your source (turntables to DAPs), if it’s physical, there’s an input. This interface feeds eight ESS Sabre ES9018 digital-to-analog converters (four DACs in parallel per channel), supporting resolutions up to 32-bit/384 kHz. Gold-vaporized ceramic electrodes to separate L/R channel paths eliminate distortion. Those, in turn, feed the vacuum tube preamplifier—all in service of reproducing summit-fi technicalities. The headset itself, found at the end of a specially tuned fabric-wrapped 99.9% silver-plated OFC cable, sits snugly thanks to luxurious, hand-sewn leather and reflection-absorbing microfiber cushions. It contains 2.4-micrometer platinum-vaporized diaphragms between conductive plates, each one powered by a Cool Class A MOSFET amplification found in a “fin” along the precision-machined aluminum ear cup. This fully decoupled power supply helps prevent electrical interference.  The result is reproduction of 8 Hz to more than 100 kHz, with distortion less than 0.01% at 1 kHz, 100 dB SPL. That translates to everything in its right place. Before he signs off on an HE 1, Damian runs extensive testing. Hundreds of cycles confirm acoustics and apparatus shouldn’t buckle under humidity or hubris. Of course, the tour isn’t just about creating an object … it’s about making an impression. And the last part of the AEC does just that. I can be told all the specs, but math just doesn’t convince me like magic. So, in a former section of the lobby now behind soundproofed doors, communion takes place. In this acoustically treated alcove, an HE 1 is unleashed. In this clean, curated space, emotion is unlocked.  Ushered into this techno-sacristy as pairs, we flip through LPs and CDs till we agree on tracks. We then push a button to trigger a transformation. The presentation of the HE 1 is equal parts mechanics and dramatics. As the motorized smoked glass cover opens and brushed metal knobs extend, eight tubes in quartz cylinders rise like treasured artifacts—amber idols that glow and growl, electrons begging to be excited, warming in antici … pation. We pick up our synced headsets, surprisingly light for something shouldering so many engineers and executives’ reputations, and settle into matching lounge chairs. The first track my duo auditions is “Angel” off the 2018 remaster of Massive Attack’s 1998 album Mezzanine. Fed from a Rega turntable, the HE 1 renders every grain and strain as the needle traces the groove. Dense, tense, deliberate bass ritualistically creeping, a lysergic whisper emerges from the claustrophobic grit. You’re wrapped in billowing sparseness, swathed in constricting reverb. This is a possession personified. Next, we try a cut from CD: “The Chain” off Fleetwood Mac’s 1977 stone classic Rumours. From the taut bass to each cymbal splash, the hi-hat brake to every scrape of nylon guitar strings, the physical interaction with instruments and atmosphere is spotlit, laid bare. The sound of Lindsey Buckingham and Stevie Nicks’ voices grappling, their heightened aggression and whispered regret, is upscaled in all its harmonious acrimony. The leap in resolution is exponential; this is the 4K HDR experience. This is unsettling clarity. This is real-time devastation. Throughout our session, the desire to analyze the method is challenged by the allure of the means. Imaging is immaculate, separation superlative. Headphones will never achieve the soundstage of properly positioned floor-standing speakers, but the HE 1 comes the closest of anything I’ve experienced. Transients can approach spicy, but it’s in service of authentic timbre. The low end isn’t about sheer physical slam so much as surgically precise impact. The HE 1 is the epitome of an audiophile experience—exacting effortlessness. It’s adding a meticulously crafted signal chain between source and destination to remove the distance between artist and listener.  Despite its thousands of components, the HE 1 doesn’t color playback. The presentation is faithful, not flattering. It’s beautiful. It’s brutal. For poorly mastered or compressed songs, anything oversaturated or exaggerated, the HE 1 is unforgiving. There’s revealing and then there’s exposed. It’s supernatural, almost studio monitor-like honesty that strips away all varnish. If the production sucks, prepare for all joy to be sucked from it. But it’s not a sterile experience. It’s the opportunity to sequester yourself inside exquisite performances. If you’re going to invest in a price-no-object personal sanctuary, this is the pinnacle of statement peace. A surprise awaits us when we emerge from our nook: We’re presented with the exact pair of 660S2 headphones we completed (in my case, the set above). Maybe it’s to protect some unsuspecting consumer from our handiwork. Maybe it’s just so we can relive our happy memories while engaging with some quality wired headphones. With its retooled aluminum voice coil and vented magnet system, the 300-ohm 660S2 is a little harder to drive. Still, paired with a good amp, it’s also more driving—punchier bass extends incisive muscularity to the highly resolving musicality. They’re not bassy, however, with no note smearing. And a more relaxed lower treble means it’s never shouty, just well-textured, sibilance-free timbre. The HD 660S2 is another refined flavor (particularly great for metal) in Sennheiser’s midrange-centric line. After receiving our creations, we conclude our day a few miles away at the Tullamore D.E.W. distillery. Because you can’t come to these reclaimed bogs without trying some alcohol. Because our ears need a cool-down lap, even if it’s while other senses get fired up. And because a whiskey tasting isn’t that far removed from our headphones tour. Both are exercises in observation—equally tactile and ephemeral impressions. Distilling is detail. It’s a symphony of compounds, carefully nudged layers working in tandem to unlock complexities. Adding a splash of H2O is a form of EQ that can sharpen microdynamics from murky to melodic. Cask-aging and condensation are a natural reverb chamber. Talk of nose bloom, mid-notes, and mouthfeel unveils depths both subtle and profound. Overtones, resonance, viscosity, attack vs. a lingering finish. Sound familiar? Sounds like the HE 1. And the magic of opening up a whiskey is like listening to a song—personal, impactful. It’s different expressions for different anatomies.  From drivers to drams—it’s a fitting coda. It’s how a sip becomes a story, much the way transducers became this tale. It’s taking the time to stop, breathe, and wonder. In the end, the parallels and point are clear: well-designed, deftly assembled headphones distill the noise, amplify the essence, open the doors of perception. And you don’t even have to go to drive through misty moors and whiskey warehouses to get some.