{"title":"Closed-Back","description":"\u003c!-- HiFiLoop | Closed-Back Headphones Collection Description | v3 (Condensed to 6 Accordions, Hardcore Archive \/ Lab Style \/ Mood-Safe) --\u003e\u003c!-- HELP ME FIND GEAR = 帮我找设备 \/ 代客寻货 --\u003e\u003c!-- MAKE AN OFFER = 立即出价 \/ 私聊议价 --\u003e\n\u003cdiv class=\"hfl-collection hfl-headphones hfl-closed-back\"\u003e\n\u003cp class=\"hfl-lede\"\u003e\u003cstrong\u003eThe HiFiLoop Closed-Back Archive\u003c\/strong\u003e indexes audiophile \u003cstrong\u003eclosed-back\u003c\/strong\u003e over-ear headphones—\u003cstrong\u003eused\u003c\/strong\u003e, \u003cstrong\u003eopen-box\u003c\/strong\u003e, and occasional rare inventory—published with unit-specific notes on \u003cstrong\u003eseal behavior\u003c\/strong\u003e, \u003cstrong\u003ecup resonance control\u003c\/strong\u003e, \u003cstrong\u003eimaging stability\u003c\/strong\u003e, and \u003cstrong\u003erevision \/ connector\u003c\/strong\u003e cues \u003cem\u003ewhen identifiable\u003c\/em\u003e.\u003c\/p\u003e\n\u003cp class=\"hfl-ctas\"\u003eIf a page shows \u003cstrong\u003eSold Out\u003c\/strong\u003e, use \u003ca href=\"#\" class=\"hfl-cta-link\" data-hfl-chat=\"find_gear\" title=\"Request sourcing by specific revision\/era (when identifiable), pad version, connector\/termination, tonal target, and system synergy\"\u003e\u003cstrong\u003eHELP ME FIND GEAR\u003c\/strong\u003e\u003c\/a\u003e. For active listings, use \u003ca href=\"#\" class=\"hfl-cta-link\" data-hfl-chat=\"make_offer\" title=\"Request a private offer on an active listing\"\u003e\u003cstrong\u003eMAKE AN OFFER\u003c\/strong\u003e\u003c\/a\u003e.\u003c\/p\u003e\n\u003cdiv aria-hidden=\"true\" class=\"hfl-divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003ch2 class=\"hfl-h2\"\u003eBrowse by Acoustic Design\u003c\/h2\u003e\n\u003cul class=\"hfl-list\"\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/open-back\" title=\"Open-Back Headphones Collection\"\u003e\u003cstrong\u003eOpen-Back Headphones\u003c\/strong\u003e\u003c\/a\u003e \u003cspan class=\"hfl-muted\"\u003e— vented architecture for decay, air, and spatial cues; optimized for quiet rooms and stage geometry.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/closed-back\" title=\"Closed-Back Headphones Collection\"\u003e\u003cstrong\u003eClosed-Back Headphones\u003c\/strong\u003e\u003c\/a\u003e \u003cspan class=\"hfl-muted\"\u003e— sealed loading for isolation and bass foundation; \u003cstrong\u003eseal + pad geometry + damping\u003c\/strong\u003e become part of the tuning.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/over-ear\" title=\"Over-Ear Headphones Collection\"\u003e\u003cstrong\u003eOver-Ear Headphones\u003c\/strong\u003e\u003c\/a\u003e \u003cspan class=\"hfl-muted\"\u003e— the full-size platform (open + closed). Clamp, pad geometry, and comfort variables matter for long sessions.\u003c\/span\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv aria-hidden=\"true\" class=\"hfl-divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c!-- Accordion (Condensed Set: 6) --\u003e\n\u003cdetails data-hfl-acc=\"\" class=\"hfl-acc\"\u003e\n\u003csummary class=\"hfl-acc__summary\"\u003eSeal Geometry \u0026amp; Pad Condition (The Bass Foundation Variable)\u003c\/summary\u003e\n\u003cdiv class=\"hfl-acc__panel\"\u003e\n\u003cp\u003eOn closed-backs, \u003cstrong\u003eseal is part of the frequency response\u003c\/strong\u003e. Pad geometry, pad compression, clamp force, and head shape (including glasses) can shift bass level, midrange density, and perceived punch. The goal isn’t “more bass” by default—it’s bass with \u003cstrong\u003estructure\u003c\/strong\u003e, controlled decay, and consistent seal behavior.\u003c\/p\u003e\n\u003cp class=\"hfl-muted\"\u003e\u003cstrong\u003ePad collapse or low-frequency leakage can mimic imbalance\u003c\/strong\u003e when one side seals differently. That’s why pad\/seal condition is treated as first-class data in our notes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails data-hfl-acc=\"\" class=\"hfl-acc\"\u003e\n\u003csummary class=\"hfl-acc__summary\"\u003eCup Resonance, Damping \u0026amp; Transient Control\u003c\/summary\u003e\n\u003cdiv class=\"hfl-acc__panel\"\u003e\n\u003cp\u003eClosed-backs trade openness for controlled loading. The technical question is how well the design manages \u003cstrong\u003ecup resonance\u003c\/strong\u003e and internal reflections without smearing transients. Strong designs preserve attack and micro-dynamics while keeping the chamber “quiet,” avoiding hollow coloration or overhang.\u003c\/p\u003e\n\u003cp class=\"hfl-muted\"\u003eDriver type is not destiny. Damping strategy, pad geometry, and amplifier control routinely matter more than the label.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails data-hfl-acc=\"\" class=\"hfl-acc\"\u003e\n\u003csummary class=\"hfl-acc__summary\"\u003eImaging Stability Under Isolation (Center-Lock \u0026amp; Localization)\u003c\/summary\u003e\n\u003cdiv class=\"hfl-acc__panel\"\u003e\n\u003cp\u003eClosed-backs can image extremely well, but the mechanism differs: seal consistency and chamber control affect \u003cstrong\u003ecenter-lock\u003c\/strong\u003e, depth cues, and treble localization. When done right, you get stable imaging with isolation—useful when open-back isn’t viable.\u003c\/p\u003e\n\u003cp class=\"hfl-muted\"\u003eIf you want “monitor-style precision” vs “dense and physical,” say so—those targets map to different damping and voicing choices.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails data-hfl-acc=\"\" class=\"hfl-acc\"\u003e\n\u003csummary class=\"hfl-acc__summary\"\u003eRevision History \u0026amp; Configuration Cues\u003c\/summary\u003e\n\u003cdiv class=\"hfl-acc__panel\"\u003e\n\u003cp\u003eClosed-backs can change meaningfully across revisions—pad updates, damping tweaks, driver batches, connector variants, and regional runs. When identifiable, we catalog revision cues (markings, serial ranges, included accessories, connector type) to help you target the right unit—not just the right model name.\u003c\/p\u003e\n\u003cp class=\"hfl-muted\"\u003eChasing a known “sweet spot” era or configuration? Use \u003cstrong\u003eHELP ME FIND GEAR\u003c\/strong\u003e and specify revision\/era + budget ceiling.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails data-hfl-acc=\"\" class=\"hfl-acc\"\u003e\n\u003csummary class=\"hfl-acc__summary\"\u003eHiFiLoop Verification + Condition Grades (What We Disclose)\u003c\/summary\u003e\n\u003cdiv class=\"hfl-acc__panel\"\u003e\n\u003cp\u003e\u003cstrong\u003eThe HiFiLoop Bench-Test Protocol\u003c\/strong\u003e indicates the unit was reviewed against a failure-focused checklist before publishing:\u003c\/p\u003e\n\u003cul class=\"hfl-list\"\u003e\n\u003cli\u003e\n\u003cstrong\u003eChannel balance \u0026amp; phase integrity:\u003c\/strong\u003e obvious anomalies screened where detectable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeal \/ low-frequency leak screen:\u003c\/strong\u003e pad\/seal asymmetry reviewed when it can impact bass foundation and perceived balance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConnection integrity:\u003c\/strong\u003e connector stability and termination condition noted when applicable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccessories \u0026amp; configuration:\u003c\/strong\u003e included items confirmed against the listing (cables, adapters, case\/box where applicable).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"hfl-muted\"\u003e\u003cstrong\u003eCosmetic grades\u003c\/strong\u003e (Mint \/ Excellent \/ Good \/ Fair) describe appearance—not “sound quality.” Wear-items (pads\/headband) are disclosed when they materially impact seal or comfort.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails data-hfl-acc=\"\" class=\"hfl-acc\"\u003e\n\u003csummary class=\"hfl-acc__summary\"\u003eConcierge Sourcing, Shipping \u0026amp; Protection (One Message Saves a Wrong Buy)\u003c\/summary\u003e\n\u003cdiv class=\"hfl-acc__panel\"\u003e\n\u003cp\u003eFor closed-backs, synergy includes \u003cstrong\u003eseal behavior\u003c\/strong\u003e, pad geometry, and how your chain controls bass decay and upper-mid energy. We can target the right \u003cstrong\u003erevision\/era\u003c\/strong\u003e and confirm configuration before you commit.\u003c\/p\u003e\n\u003cp\u003eOrders are inspected before dispatch. Typical processing is \u003cstrong\u003e3–5 business days\u003c\/strong\u003e, and international delivery commonly ranges \u003cstrong\u003e7–15 days\u003c\/strong\u003e depending on destination. Free shipping over \u003cstrong\u003e$199\u003c\/strong\u003e; otherwise \u003cstrong\u003e$9.99\u003c\/strong\u003e. Backed by HiFiLoop Protection (14-Day DOA + eligible service coverage, item-dependent).\u003c\/p\u003e\n\u003cp class=\"hfl-muted\"\u003eSend: budget range, chain (source\/DAC\/amp), glasses\/no-glasses, listening volume, and what you want to avoid (cuppy coloration, treble edge, mid-bass bloom). We’ll reply with a short technical shortlist.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdiv aria-hidden=\"true\" class=\"hfl-divider\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cp class=\"hfl-cta-bottom\"\u003e\u003cstrong\u003eNeed a specific closed-back revision—or optimizing seal + synergy?\u003c\/strong\u003e Use \u003ca href=\"#\" class=\"hfl-cta-link\" data-hfl-chat=\"find_gear\" title=\"Request sourcing via concierge\"\u003e\u003cstrong\u003eHELP ME FIND GEAR\u003c\/strong\u003e\u003c\/a\u003e and include your budget, chain, glasses\/no-glasses, typical listening volume, and what you want to avoid (cuppy coloration, treble edge, mid-bass bloom).\u003c\/p\u003e\n\u003c\/div\u003e","products":[{"product_id":"edifier-stax-spirit-s5-headphones-used","title":"Edifier STAX SPIRIT S5 Wireless Headphones - Mint - Verified by HiFiLoop","description":"\u003cdiv\u003e\n  \u003ch2\u003eThe Audiophile's Hook\u003c\/h2\u003e\n  \u003cp\u003e\n    STAX SPIRIT S5 is the rare thing: a true wireless planar headphone built for “detail-first” listening without giving up everyday convenience.\n    This unit is Mint (99% new) and includes the full retail set—serious performance-per-dollar, verified by HiFiLoop.\n  \u003c\/p\u003e\n\n  \u003ch2\u003eCondition Report (The Truth)\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003eMint \/ Collector Quality:\u003c\/strong\u003e Like new with minimal handling marks.\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eNo obvious cosmetic defects observed.\u003c\/li\u003e\n    \u003cli\u003eFull retail set included (box and accessories as shown in the listing photos).\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eMandatory:\u003c\/strong\u003e The device has passed all functional tests.\u003c\/p\u003e\n\n  \u003ch2\u003eSonic Signature \u0026amp; Pairing\u003c\/h2\u003e\n  \u003cp\u003e\n    S5 is built around planar speed and separation, aiming to uncover fine details while staying engaging and energetic. It also supports multiple high-quality Bluetooth codecs for modern hi-res wireless chains.\n    If you prefer wired listening, S5 supports USB-C and AUX connections for flexible setups.\n  \u003c\/p\u003e\n  \u003cp\u003e\n    To unleash the full potential of this device, we recommend pairing it with gear from our \u003ca href=\"\/collections\/amplifiers-dacs\"\u003eAmplifiers \u0026amp; DACs Collection\u003c\/a\u003e.\n  \u003c\/p\u003e\n\n  \u003ch2\u003eTechnical Highlights (Mobile-Table)\u003c\/h2\u003e\n  \u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eBluetooth\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eBluetooth 5.4\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003ePlaytime\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eAround 80 hours\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eFrequency Response\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e10Hz–40kHz\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eAudio Codecs\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eSnapdragon Sound, aptX Lossless\/Adaptive\/HD, LHDC, LDAC, SBC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eNet Weight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e347g\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eCharging Port\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eUSB-C (Type-C)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eEdifier STAX SPIRIT S5 headphones\u003c\/li\u003e\n    \u003cli\u003eFull retail packaging and accessories (as shown in listing photos)\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003eWhy Buy Used from HiFiLoop?\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003e✅ 14-Day DOA: Full refund\/replace if dead on arrival.\u003c\/li\u003e\n    \u003cli\u003e🔧 180-Day Warranty: Free repair service (buyer pays return shipping).\u003c\/li\u003e\n    \u003cli\u003e🔬 Lab Tested: Connectivity, channel balance, and basic functional integrity verified.\u003c\/li\u003e\n    \u003cli\u003e📦 Free Shipping: On orders over $199.\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eSee full Grading Scale in Footer Condition Guide.\u003c\/strong\u003e\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eCTA:\u003c\/strong\u003e Missed this? Contact “Help Me Find Gear”.\u003c\/p\u003e\n\u003c\/div\u003e\n","brand":"HiFiLoop","offers":[{"title":"Default Title","offer_id":47614691868886,"sku":null,"price":279.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0790\/7445\/9862\/files\/Used_Edifier_STAX_SPIRIT_S5_wireless_planar_headphones_in_Mint_condition_-_product_photo.jpg?v=1765965185"},{"product_id":"sennheiser-hd-620s-headphones-used","title":"Sennheiser HD 620S Closed-Back Headphones - Mint - Verified by HiFiLoop","description":"\u003cdiv\u003e\n  \u003ch2\u003eThe Audiophile's Hook\u003c\/h2\u003e\n  \u003cp\u003e\n    The Sennheiser HD 620S is the rare closed-back that still feels open: focused isolation with speaker-like imaging, fast transients, and reference detail that doesn’t collapse your stage.\n    This unit is Mint (99% new) and comes as a full set—flagship listening value, verified by HiFiLoop.\n  \u003c\/p\u003e\n\n  \u003ch2\u003eCondition Report (The Truth)\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003eMint \/ Collector Quality:\u003c\/strong\u003e Like new with minimal handling marks.\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eNo obvious cosmetic defects observed.\u003c\/li\u003e\n    \u003cli\u003eFull retail set included (box and accessories as shown in the listing photos).\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eMandatory:\u003c\/strong\u003e The device has passed all functional tests.\u003c\/p\u003e\n\n  \u003ch2\u003eSonic Signature \u0026amp; Pairing\u003c\/h2\u003e\n  \u003cp\u003e\n    HD 620S is designed for distraction-free listening without the “boxed-in” feeling: clear separation, stable imaging, and an airy presentation for a closed-back.\n    It scales noticeably with a clean DAC\/amp—tighter control, stronger dynamics, and a darker background.\n  \u003c\/p\u003e\n  \u003cp\u003e\n    To unleash the full potential of this device, we recommend pairing it with gear from our \u003ca href=\"\/collections\/amplifiers-dacs\"\u003eAmplifiers \u0026amp; DACs Collection\u003c\/a\u003e.\n  \u003c\/p\u003e\n\n  \u003ch2\u003eTechnical Highlights (Mobile-Table)\u003c\/h2\u003e\n  \u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eDesign\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eCircumaural, closed-back, dynamic\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eTransducer\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e42mm angled transducers (38mm diaphragm noted by Sennheiser)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eImpedance\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e150Ω\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eFrequency Response\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e6 Hz – 30 kHz\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e326 g (without cable)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eCable\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eDetachable 1.8m cable, 3.5mm plug + screw-on 6.3mm adapter\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eSennheiser HD 620S closed-back headphones\u003c\/li\u003e\n    \u003cli\u003eDetachable 1.8m cable (3.5mm)\u003c\/li\u003e\n    \u003cli\u003e3.5mm to 6.3mm screw-on adapter\u003c\/li\u003e\n    \u003cli\u003eStorage pouch (if shown in photos)\u003c\/li\u003e\n    \u003cli\u003eRetail box and accessories (as pictured)\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003eWhy Buy Used from HiFiLoop?\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003e✅ 14-Day DOA: Full refund\/replace if dead on arrival.\u003c\/li\u003e\n    \u003cli\u003e🔧 180-Day Warranty: Free repair service (buyer pays return shipping).\u003c\/li\u003e\n    \u003cli\u003e🔬 Lab Tested: I\/O, noise floor, channel balance verified.\u003c\/li\u003e\n    \u003cli\u003e📦 Free Shipping: On orders over $199.\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eSee full Grading Scale in Footer Condition Guide.\u003c\/strong\u003e\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eCTA:\u003c\/strong\u003e Missed this? Contact “Help Me Find Gear”.\u003c\/p\u003e\n\u003c\/div\u003e\n","brand":"HiFiLoop","offers":[{"title":"Default Title","offer_id":47669002862806,"sku":null,"price":189.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0790\/7445\/9862\/files\/Used_Sennheiser_HD_620S_closed-back_headphones_in_Mint_condition_-_product_photo.jpg?v=1767001558"},{"product_id":"sennheiser-hdb-630-wireless-headphones-used","title":"Sennheiser HDB 630 Wireless ANC Headphones - Good - Verified by HiFiLoop","description":"\u003cdiv\u003e\n  \u003ch2\u003eThe Audiophile's Hook\u003c\/h2\u003e\n  \u003cp\u003e\n    The Sennheiser HDB 630 is built for “audiophile-first” wireless: a closed-back design with serious detail, strong isolation, and a battery that’s made for day-long listening.\n    This is a high-value used listing—flagship performance for less, verified by HiFiLoop.\n  \u003c\/p\u003e\n\n  \u003ch2\u003eCondition Report (The Truth)\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003eGood \/ Workhorse Condition:\u003c\/strong\u003e Visible cosmetic wear, but ready for daily use and strong value for the category.\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eCosmetic bumps and surface wear present (as pictured).\u003c\/li\u003e\n    \u003cli\u003eFull retail set included (box and accessories as shown in the listing photos).\u003c\/li\u003e\n    \u003cli\u003eHeadphone stand included.\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eMandatory:\u003c\/strong\u003e The device has passed all functional tests.\u003c\/p\u003e\n\n  \u003ch2\u003eSonic Signature \u0026amp; Pairing\u003c\/h2\u003e\n  \u003cp\u003e\n    HDB 630 targets a neutral, high-resolution presentation with focused listening in mind—great for commuting, office sessions, and late-night detail dives.\n    Use the Smart Control Plus app to fine-tune with parametric EQ and features like crossfeed when you want a more speaker-like blend.\n  \u003c\/p\u003e\n  \u003cp\u003e\n    To unleash the full potential of this device, we recommend pairing it with gear from our \u003ca href=\"\/collections\/amplifiers-dacs\"\u003eAmplifiers \u0026amp; DACs Collection\u003c\/a\u003e.\n  \u003c\/p\u003e\n\n  \u003ch2\u003eTechnical Highlights (Mobile-Table)\u003c\/h2\u003e\n  \u003ctable style=\"width:100%; border-collapse: collapse;\"\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eDesign\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eClosed-back wireless headphones with Adaptive Noise Cancellation\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eDriver\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e42mm dynamic drivers\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eBluetooth\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eBluetooth 5.2 with aptX Adaptive support\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eHi-Res Playback\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eUp to 24-bit\/96 kHz via USB-C or 3.5mm wired connection\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eBattery Life\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eUp to 60 hours (claimed, ANC on)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003e\u003cstrong\u003eIncluded Dongle\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 8px; border-bottom: 1px solid #eee;\"\u003eBTD 700 USB-C Bluetooth dongle (part of standard box contents)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/table\u003e\n\n  \u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eSennheiser HDB 630 headphones\u003c\/li\u003e\n    \u003cli\u003eFull retail box and accessories (as shown in photos)\u003c\/li\u003e\n    \u003cli\u003eHeadphone stand\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003eWhy Buy Used from HiFiLoop?\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003e✅ 14-Day DOA: Full refund\/replace if dead on arrival.\u003c\/li\u003e\n    \u003cli\u003e🔧 180-Day Warranty: Free repair service (buyer pays return shipping).\u003c\/li\u003e\n    \u003cli\u003e🔬 Lab Tested: Connectivity, noise floor, and channel balance verified.\u003c\/li\u003e\n    \u003cli\u003e📦 Free Shipping: On orders over $199.\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eSee full Grading Scale in Footer Condition Guide.\u003c\/strong\u003e\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eCTA:\u003c\/strong\u003e Missed this? Contact “Help Me Find Gear”.\u003c\/p\u003e\n\u003c\/div\u003e\n","brand":"HiFiLoop","offers":[{"title":"Default Title","offer_id":47669074034902,"sku":null,"price":549.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0790\/7445\/9862\/files\/Used_Sennheiser_HDB_630_wireless_ANC_headphones_in_Good_condition_-_product_photo.jpg?v=1767002123"}],"url":"https:\/\/www.hifiloop.com\/collections\/closed-back.oembed","provider":"HiFiLoop","version":"1.0","type":"link"}