12VDC. The Clean not Dirty Dozen? Before we rename a famous movie—ex director Thorsten Loesch¹ at right—let's roll another matter: discrediting switching supplies. After all, anything built to a price risks being overshadowed by the more advanced. Because our sector never seems to upgrade a built-in linear supply with an external switcher, the popular takeaway is that linear power must beat switching power. Not so fast. Consider this from a 2018 interview with EveAnna Manley: "A few years ago I contracted one of the most brilliant minds on the planet, Bruno Putzeys—then with Hypex now of Kii Speakers—to custom design for us a really advanced switch-mode power supply specifically for our vacuum-tube audio circuits. Gone is all hum! This new supply has all regulated rails that create much lower impedance than the older linear designs. It runs at 125kHz so there's no more 50/60Hz hum in the chassis. It's also a very low-radiating implementation and rarely requires additional metal screening. It's really quiet. It also has a universal voltage primary so works anywhere in the world without reconfiguration. But the most important thing is that Bruno designed this supply for superior sound quality and this new tech beats the old supplies in listening tests every time. I'm pretty sure that we have the most advanced vacuum-tube power supply design amongst my peers in the audio world."

From Aavik to Alberto Guerra Production, Chord to Crayon, Gold Note to LinnenberG and Nagra, numerous modern hifi kit exploits switching power for the same reasons as Manley. As elsewhere, there are layers, levels and leagues to things. Blanket statements are too woolly. Now we're ready to consider today's scenario which doesn't upgrade a wall wart but bigger purpose-designed 30W switch-mode supply built into the device with an external switch-mode supply. And while we're at it, there's another reason why squeaky-clean listeners prefer linear power. They don't want switching power's HF noise migrating down their AC loom into other hifi gear. But if that thinking is unaccompanied by a domestic ban on local WiFi and Bluetooth, it's just lip service. We shut down a just potential noise source—most SMPS in computers for example must comply with stringent emission regs to be well shielded—whilst activating new most definitive noise sources that radiate freely everywhere to be the opposite of contained and shielded. That's not rigorous and consistent thinking. That's playing favourites. iFi too are guilty of this with products whose WiFi/Bluetooth transmitters are permanently active and can't be disabled. I had to return my personal iDSD Pro Signature to the UK HQ to have their tech remove its transmitter permanently. The futuristic very clever high-performance iFi Aurora below too was a default UHF radiator without any defeat option. But obviously WiFi isn't the only source of hifi noise. Now we're right back at the iPower Elite. It proposes to retire lesser noisier power supplies to make the equipment connected to those perform better – by being itself a more ambitious switch-mode power provider. My sample didn't ship from Blighty but iFi's Warsaw warehouse for zero VAT customs hassles.

¹ From a 2019 AMR/iFi press release: "John Curl will now work across all new design projects for Southport-based sister companies iFi Audio and Abbingdon Music Research. Curl will be collaborating closely with iFi's technical director Thorsten Loesch to ensure that all circuit designs are fully optimised. John's place in high-end audio's hall of fame was cemented when he developed the complimentary differential-input circuit while building the Grateful Dead's mixing console in 1968. Additionally Curl worked with a young Mark Levinson in the early 1970s to create the now legendary Mark Levinson Audio Systems JC-2 preamplifier. The JC-2 was the first standalone product to incorporate Curl's complementary differential-input circuit. The JC-2 was then followed by the ML-2 Class A power amplifier. Since then John Curl went on to work with many other luminaries of the high-end audio scene, including Dave Wilson and Jeff Roland, with his own company Vendetta Research and later as contract engineer for Parasound." According to this, after 13 years at the helm of AMR and iFi so also 2019, Thorsten Loesch became an independent consultant to the consumer electronics industry at large and relinquished his former post as iFi's technical director. Yet this clearly didn't stall the glut of products which iFi's brain trust has issued since. Meanwhile Thorsten's LinkedIn page announces new products no longer under AMR/iFi branding. Whether we'll learn of his involvement depends on whether he contributes as anonymous OEM consultant or gets formally credited again.

Here we see the R7's lone two rear cables, one a Forza Audioworks custom USB-C/B signal link from Poland, the other iFi's power umbilical with ferrite barrel.

Here's the full-frontal show with custom Forza XLR4 cabling for Meze's 109 Pro then iFi's SMPS in sideview fed by the original Zu power cord.

My hands were ready to switch one power cord back and forth as often as it took for my ears to cast their vote. If iFi won the day, I'd not know whether it was due to plain superiority; and/or from going offboard to eliminate a source of UHF radiation right next to FiiO's signal circuity. The latter is the general rationale for dirty/clean box kit where the signal circuits sit in one, the power supply in another chassis to practice divide 'n' conquer.