When it comes to portable hi-fi streamers, nobody is more highly respected in the audiophile community than Astell&Kern. Last year, the Korean firm replaced its top-shelf SP3000 with the SP4000, a digital audio player (DAP) in the A&Ultima range that upgrades its predecessor’s audio circuitry, noise reduction, processing, and usability, aiming for even cleaner, more dynamic hi-fi playback. It also listened to customer feedback by introducing complete Android OS to the fray for the first time.
Now, A&K have come out with a special Copper Edition of the SP4000, adding $200 to the price tag but giving us perhaps the best-looking DAP on the planet.
Engineering Excellence Meets Material Science
Copper has always been a theoretical darling in audio circles, boasting exceptional electrical conductivity and superior electromagnetic shielding. But working with 99.98% pure copper is a nightmare. The material oxidizes rapidly and deforms under even minor machining stress. Rather than shy away from these challenges, Astell&Kern developed a multi-layer stabilization process that requires serious technical expertise to pull off. The result is a portable player that weighs 22.6oz (about an ounce heavier than the stainless steel version) and delivers what A&K describes as deep, authoritative bass, a dense midrange, and treble that fades naturally.
This isn’t their first rodeo with copper. The AK380 got a similar treatment nearly a decade ago. However, the SP4000 Copper pushes the concept further, framing it less as a cosmetic upgrade and more as sonic refinement.
The SP4000 Foundation
Underneath that lustrous exterior sits the same hardware that made the standard SP4000 a benchmark: true quad-DAC architecture with four AK4191 digital processors paired 1:1 to four AK4499EX DACs, achieving a 131dB signal-to-noise ratio. High Driving Mode doubles parallel OPAMPs for expanded dynamic range without sacrificing clarity, while proprietary ESA (Enhanced Signal Alignment) technology minimizes group delay across frequencies. There’s also an Ultra Low Noise LDO Regulator that’s 97% quieter than previous generations — borrowed from medical devices and 5G equipment — and a 99.9% pure copper Shield Can for EMI blocking.
The 6-inch 2K touchscreen runs full Android, supports PCM up to 32-bit/768kHz and DSD512, and delivers around 10 hours of playback. Outputs include unbalanced 3.5mm (4.1Vrms), balanced 4.4mm (8.2Vrms), and optical. This is simply the best DAP you’ll find. That is, if you’re willing to shell out the dough.
Spec Sheet
Model: A&Ultima SP4000 Copper Limited Edition
Body Material: 99.98% Pure Copper
Weight: 22.6oz
Display: 6-inch 2K (2160 x 1080) touchscreen
DAC: AK4191 x4 + AK4499EX x4 (Real Quad DAC)
Battery Life: ~10 hours playback
Operating System: Full Android OS
Outputs: 3.5mm unbalanced, 4.4mm balanced, 3.5mm optical
Supported Formats: PCM up to 32-bit/768kHz, DSD512
Pricing & Availability
The A&Ultima SP4000 Copper Edition is available now for $4,100, a $200 premium over the standard black and silver models priced at $3,999. Astell&Kern hasn’t disclosed production numbers, but given the difficulty of working with pure copper and the limited edition designation, don’t expect these to stick around long.
Recap
Astell&Kern A&Ultima SP4000 Copper Edition
Astell&Kern just dropped a Copper Edition of its flagship SP4000 DAP, wrapping the same powerhouse internals in 99.98% pure copper for $4,100 — a $200 bump that delivers a stunning look and what the brand claims is a warmer, more natural sound signature. It’s a limited run that required serious engineering chops to pull off, making it arguably the best-looking portable players you can buy right now.
