Double/quad opa trouble

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Tahoe 26), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Gustard U26 USB bridge, LHY Audio SW-8 & SW-6 switch, Sonnet Pasithea; Preamp: Hattor Audio ARP-S; Active filter: spl Audio Crossover MkII; Power amplifiers: Vinshine/Kinki Dazzle & Audiophonics NCx500 on subwoofer; Loudspeakers: Qualio IQ [on loan]; Subwoofer: sound|kaos D15; Cables: Exact Express Flame, Furutech; Power delivery: 2 x Kinki/Vinshine Tai Hang on amps and source stack, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, AudioQuest FogLifters; Room: 6 x 8m with open door behind listening seat; Room treatment: 2 x PSI Audio AVAA C214 active bass traps
1st upstairs speaker system: Source: Shanling EM7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe with POW; Preamp/filter: Lifesaver Audio iCon 4SE & Gradient Box 2; Amplifier: Kinki Studio EX-B7 monos; Loudspeakers: sound|kaos Vox3awf; Subwoofer: sound|kaos D12 on twin Nord Acoustic NC500 monos; Cable loom: Exact Express Earth; Power delivery: Vibex Granada/Alhambra, Akiko Audio Corelli Corundum & Castello Solo; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Furutech cable lifts, Furutech NFC Clear Lines; Room: ~3.5 x 8m
1st upstairs headfi system: DAC: Cen.Grand DSDAC 1.0 Deluxe with POW; Headamp: Cen.Grand Silver Fox; Headphones: Raal 1995 Magna, HifiMan Susvara
Desktop system: Source: HP Z2 workstation Win11/64; USB isolator: LHY UIP; LAN distributors: LHY AS6 Pro & SW6-SFP; Ethernet reclocker: Stack SmoothLAN; DACs: Gustard R26II & Audalytic DR70; Preamp: Topping A900; Speaker amps: Topping B200 monos; Headphone amp: Enleum AMP-23R; Loudspeakers: Virtual Hifi Viper; Headphones: Final D-8000, aune SR7000, FiiO FT7, HifiMan Susvara Unveiled
2nd upstairs headfi system: Shanling EM5; Headphones: Meze 109 Pro, Fiio FT3, HifiMan HE1000 Unveiled
2nd upstairs speaker system: Source: smsl PL200T CD transport; DAC: Shanling EM7 w. 1TB microSD; Crossover: Lifesaver Audio Gradient Box II;  Amplifiers: LAIV Crescendo Chorus monos; Loudspeakers: MonAcoustic SuperMon Mini with Dynaudio S18 subwoofer
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: ModalAkustik MusikBoxx; Subwoofer: 2 x Zu Method; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: from €35.67 – €91.02 per unit

"Recently discrete opamps have become popular. Because they're built from separate components, many believe that they sound better than integrated versions. And it's true that good discrete opamps can sound fantastic. However, there's another way to get incredible performance: connect several of the best modern chip-based opamps in parallel to deliver more power, improve control and lower noise for increased dynamics, substance, bass control, presence and a wider soundstage. In many cases, two top-quality integrated opamps working together can outperform a typical discrete design." That was Grzegorz Rulka of Virtual Hifi who offers a tidy range of multi-paralleled hot-swappable chip-based opas. I recently had opportunity to try three versions of his in my Audiophonics NCx500 nCore amp whose stock 1656 input opamp shows at right. When hot-plugging socketed opa, directionality is critical. Dispute it for cables. Bully for you. But misinsert an opamp and your bull draws blood. It's smoke you don't want. So look for the little crescent as either a printed marker or actual physical indent on the opamp and PCB. It'll tell you which end of the 8-legged critter is 'north'. Child's play if you know to do it. Silly mishap if you don't. Next we see Grzegorz's care package delivered in 3D-printed round pill boxes with lock tops. Those should subsequently find use for vitamins, daily meds, spices or powders. They're too nice to discard.

The twin arrows here and below point at Audiophonics' stock opamps.

Because already my amp's opa receiver sockets sit proud of the board, installing the Virtual opamps parks them well above the PCB like holey mushrooms on stems. There's no worry over extra downward temps roasting the circuit board from undue proximity. Regarding the extra current draw from doubling or quadrupling opamp loads, check with Grzegorz about your component, which of his opamps you mean to use and how many your application needs. "These run hot. However, their max temperature is ~80°C and the chips along with all passive components are designed to work stably to 125°C. Of course all electronic chips experience long-term heat degradation so they won't last forever. That said, hundreds of customers and I have now been enjoying the hot-running Hypersonics for over two years of daily use and they continue to work flawlessly. As long as you don't use them in a very small confined enclosure, you'll be fine. Just think of them as solid-state tubes. The Blue Supersonic V2 are my bestsellers and the Hypersonics are best for full-bodied sound. They're based on the same chips as the Supersonic V2. In essence they are doubled-up Supersonic V2 so you can really hear what doubling/paralleling does to the sound signature. It's interesting how many electronics engineers conclude there's no sonic difference because they cannot see one on their oscilloscopes."

On my desktop for easy plug 'n' play, going green opamps immediately densified the ultra-feedback class D amp's dry highly damped sonic profile. Everything grew evenly and profoundly more chunky. This was no chocolate excess or baklava dripping in sugar syrup. All was proper grippy and taut but with an unapologetic clockwise twirl on an imaginary incarnation knob. Beam me down more, Scotty. After powering the amp off, swapping to blue caused an involuntary jerk. After just 10 minutes of use, the greenie tops were scalding. Lesson learnt. Needle-nose pliers to the rescue. Why wait for my shrooms to cool to finger fitness? Hot stuff! The blue chaps sounded decidedly different; more forward, more separated, with more top-end energy, lower density and less gravitational anchoring. This still fully overhauled the flatter greyer stock voicing but pursued more resolution and apartheid than team green. Between the two, my proclivities favoured blue. Big Red then hunkered down roughly in-between. It dealt out equal hands for subjective resolution and weight but had even more teased-out refinement and presence to sit higher than either. Personally most positive about playing plucky pliers? No matter the colour, this Polish lot overwrote my misgivings over the dry overdamped stock sound. That I'd not expected when personal assumptions had blamed intense negative feedback in the mid/high bands for overdamping the gestalt. Wrong guess? Whittling things down to my favourite Virtual opa, green was out first. My pick for a desktop resident was between blue and red. Picking out opamps was great fun whilst Volkan Konak's joy-filled vocals showed the way. Given my favouritism of teased-out treble, blue was the winner.

But—my NCx500 amp wouldn't loiter around my office where Topping B200 monos fill the amp slots. For pure subwoofer glory below 120Hz/4th-order powering a passive dual 15" folded-dipole bass maker, would blue blood still take the crown? To decide, I cued up "Oriental Bass" from Patrick Chartol's Istanbul album. Set on endless repeat, hitting 'pause' plucked 'n' pinned opamps with my trusty pliers. Blue disqualified first, red next. For the sub, I'd play it Gaelic so green for proper whomp and circumstance. Truth told, I just needed extra assurance. With their strong dissipation, was long-term use of these little hotties perfectly safe and tested? It's been a long time since I burnt skin on a scalding tube whilst otherwise naught bad happened. Peace of mind simply needed a reminder that toasty opamps were equally fine. Skin grows back. Burnt circuits do not. As already covered, Greg had that answer.

Suffice to say that unlike the oscilloscope deniers, my rolling showed very obvious changes. Which flavour one prefers is personal. There simply can be no argument that swapping this crew needs golden ears to make out. Ordinary lead ears will do just fine. For sub duty, mine would start off in lime like Kermit the frog. I could always chameleon later and change colours. Before departing my desktop, it's fair to reiterate how this opamp exercise rather modified my original opinion on the NCx500 for full-range speaker drive. Wearing blue, I'd happily listen to it as the office's main amp. At €108/pr, this would be one very cost-effective upgrade. Which colour would win out across the hallway fronting the big RiPol sub? Plain black. Huh? The more I considered it, the more the conceptual clash of ultra-efficient cool class D and searing opamps radiating like high-bias class A champs caused me mental constipation particularly when as woofer driver, my crossover's bass pot could compensate the difference in density. So this Chicken Little returned to his stockers when sonic sacrifices for that 2½-octave application were slim. On my office speakers however, I'd only enjoy the NCx500 amp virtualized, preferably in blue. In stock form my ears call it rather too dry—desickated to make up a combo term. But again, what's overcooked for midrange and treble can be absolutely ideal below 100Hz where room ringing adds its own body.  So I opted for cooler running.

To wrap, the delta of sonic profile shifting available from strategic opamp rolling was unexpectedly large with my particular Audiophonics implementation and the Virtual Hifi drop-ins. With a per-unit cost of ~€35 to €90, this is a very cost-effective way to scale up a value-priced amplifier platform like this repackaged nCore and have it perform noticeably different by supplying a higher-current signal to the speakers.