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Reviewer: Srajan Ebaen
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Main system: Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Audirvana 3, Qobuz, Tidal, Singxer SU-6 USB bridge, LHY Audio SW-8 switch, Sonnet Pasithea DAC; Active filter: icOn Gradient Box 2; Power amplifiers: Kinki Studio EX-B7 monos, Enleum AMP-23R, Goldmund/Job 225 on subwoofer; Headamp: Cewn.Grand Silver Fox; Phones: HifiMan Susvara, Meze 109 Pro; Loudspeakers: sound|kaos Vox 3awf + sound|kaos DSUB15 on Carbide Audio footers, Audio Physic Codex, Qualio IQ [on loan] Cables: Complete loom of Allnic Audio ZL; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 6 x 8m with open door behind listening seat
2nd system: Source: Soundaware D300Ref SD transport clock-slaved to Denafrips Terminator +; Preamp/filter: icOn 4Pro + 4th-order/80Hz; Amplifier: Crayon CFA-1.2; Loudspeakers: MonAcoustic SuperMon Mini or Acelec Model One + Dynaudio S18 sub; Power delivery: Furutech GTO 2D NCF; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~3.5 x 8m
Desktop system: Source: HP Z230 work station Win10/64; USB bridge: Singxer SU-2; Headamp/DAC: iFi iDSD Pro Signature; Headphones: Final D-8000; Active speakers: DMAX SC5
Upstairs headfi/speaker system: Source: smsl Dp5 transport; DAC: Auralic Vega; Integrated amplifier: Schiit Jotunheim R; Phones: Raal-Requisite SR1a; Active DSP speakers: Fram Midi 120
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: €5'150
Photos by Dawid Grzyb.
Passed out, over or up. When it comes to Pass Labs, we've seen all the passable puns. Today continues where this left off. Read it to paint the full picture; and appreciate why today is all about five years later. For me it means new room, new speakers, new active crossover, new subwoofer, new DAC, new USB bridge. All good things are six after all. The only items that haven't changed are my music iMac with Audirvana; and moi. But I can't really be sure that I haven't changed. Age, experience and taste are all moving targets. So when the opportunity arose to revisit the smallest of the Pass Labs stereo amps, I jumped at the chance to reacquaint myself with one that got away.
Photos by Dawid Grzyb. Use mouse-over loupe function; or right-click to open in new tab for full size.
Five years on, I listen to class A/B direct-coupled amps of very high bandwidth like Kinki's EX-B7 monos, Crayon's CFA-1.2 and Enleum's AMP-23R. Both upstairs/downstairs systems now anchor via subwoofer integrated by active analog outboard xover. That also precedes the main speakers with an 80Hz/4th-order Linkwitz-Riley high pass. In the smaller system, those speakers are mini monitors with isobarically doubled 4" Alpair widebanders plus ATM super tweeter. The sub is a 2 x 9½" Dynaudio.
Downstairs it's hybrid open baffles around a 6" SB Acoustic Satori dipole midrange with dipole Mundorf AMT tweeter mated to a ported 9½" Satori woofer in a big bass bin. The sub is a 2 x 15" cardioid/Ripol affair. How would the XA-25 slot in now?
Let's start upstairs. Here Enleum's 25wpc power seems perfectly equal but when relaxed to 1% THD up from 0.01%, the XA-25 triples its published rating whilst costing $1'000 less than the Korean. Also, its 800w/40A output devices are a different breed than Enleum's. Their smaller power supply is already down to 45 watts into 4Ω. The XA-25 keeps stubbornly doubling to 100wpc into 2Ω—200 watts peak—and claims stability into ½Ω.
Not all watts are created equal or accompanied by the same current. Finally there's class A vs A/B so always on vs switched transistors. That said, being already down 6dB at 80Hz given my actively high-passed mains, neither amp was tasked with bearish bass burdens. With those out of the way, how would the remaining bandwidth react to swapped drive?
Before we find out, one more bit of confessional housekeeping. These small metallic widebanders are lively types which suits my mostly low SPL in this room perfectly. However, after a power-line upgrade to Akiko Audio's Corelli and a DAC upgrade to Cen.Grand's best DSD1'024 deck, overall liveliness had grown just a bit too fresh at times.
Rather than DAC direct through its analog ladder-on-a-Muses-chip volume, I'd inserted Vinnie Rossi's L2 Signature linestage fitted with my favorite Elrog ER50 power triodes. Run in grounded-grid mode without output transformers or coupling caps to be of exceptional bandwidth, this insertion injected the desired textures which the decisive uptick in overall resolution handled without any clarity confusion. Going in I assumed that with the XA25, I could probably remove the L2 and arrive at very equivalent sound. Now we've pegged my hardware and wetware scenario to key into sonic changes.
Photos by Dawid Grzyb
… to be continued…
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