It's a lot of functionality under one compact hood. No wonder Billy Bob had to get busy frontside and back. It's actually hard to imagine just what else our designer could have crammed inside.

Purists will predictably wrinkle their noses. They don't grasp the appeal of multi-tasking and giving the customer maximum functionality. Others will poo-poo the minor bling of cosmetic gold accents. It's why purists don't get invited to parties. They're no fun.

Meanwhile iFi Audio are the Schiit of the East: irreverent, imaginative and high on value for money. They get a free pass with bouncers everywhere.

Not that they're just from the East. Abbingdon Music Research are a British company who own a factory in China. Western engineering and standards meet offshore labor advantages.

So there's a lot of hybrid surrounding Billy Bob: how he processes digital bits; how he can combine tubes with bipolar drivers and Mosfet outputs; how he can convert PCM to high-rate DSD; and how the company organizes.

It's the best-of-both-worlds idea applied to different areas. Among dog fanciers, it's well-known that the purebreds have all the issues. It's the mutts which are smarter, healthier and cheaper. It's one more nail in the purist coffin; another Pro argument for the iDSD Sig.

[What makes the iPower Elite tick at right.]

What I wanted to know (self interest alert!) was whether it could cast any shade on our upstairs legacy discrete R2R Denafrips Terminator. Arnie's lack of low-level resolution—that is, compared to Aavik's D-180 thru D-580 converters as I'd done recently—had begun to bug me on the sound|kaos speaker system so moved into the Raal ribbon headfi rig. Of course the Danish DACs price out from €6-20K. Getting more res without paying through the noose was the mission I'd chosen to accept. Would this iFi become myFi?

Lucky for me, their Victoria Pickles had a journeyman unit willing to make tracks to Ireland. I'd know soon enough. About the standard Pro iDSD which today's Signature improves upon, regular Warsaw contributor Dawid already had the dirt three years ago – including this next photo.

As you'll predict from this intro, my personal curiosity centered on straight-ahead PCM playback without DSD or tubular injections though I'd certainly pick a favorite reconstruction filter if I could hear any differences between them. Of course I'll cover the other options as well. I simply expected that as a potential upgrade to our upstairs resident, 'purist' mode would have my mutt-ering vote.

Here it's instructive to point at a competitor also concerned by R2R's limitations in the less/least significant bits: Metrum/Sonnet and their engineer Cees Ruijtenberg. Rather than interleave R2R with ΔΣ like Thorsten Loesch does to increase low-level resolution, the Dutch engineer splits his 24-bit signal into two 12-bit R2R halves to process both as most/more significant bits in multi-paralleled 24-bit ladders. He only adjusts the now hot half's excess gain in the analog domain. Same insight, different solution.

It nicely reiterates how despite iFi's 'populist' high-value positioning, the engineering baked into particularly their top models is top shelf. We shouldn't let small size, buzz-word propaganda and unusual featurization gloss over that fact. For example, the long form of GMT is "an ultra-low jitter quartz-driven clock capable of producing over 28'000'000 different frequencies. When engaged, it intelligently and dynamically controls the clock that drives the DAC chips and streams data from the memory buffer. The GMT clock is set to match the principal frequency of the incoming clock with better than 0.001Hz precision. So if the frequency drifts from 192'000.002Hz to 192'000.003Hz over a period of minutes as the meaningful minimum, GMT intelligently and precisely tracks the change.

"Once it has correctly calculated the incoming clock, the rate of updating the DAC's clock with the minimal 0.001Hz step (~0.004ppm accuracy) is at most once every few minutes or less. As a result, the DAC clock completely decouples from the source and is completely stable. With the GMT clock that drives the DAC chips and clocks the data from the memory buffer at the same exact frequency as the incoming clock, there is zero jitter in the source clock as there is no physical phase-lock loop link between source clock and clock driving the DAC chips. The GMT System is not a secondary PLL as used in some cases since the late 1990s but an entirely new concept that completely blocks jitter and only compensates any slow drift in the clock source or to adapt to a change in sample rate."

Here is the detail behind the GTO or Gibbs Transient Optimized filter as another piece of proprietary AMR/iFi tech inside the Pro iDSD Signature. And finally, some insider info on the GE5670 triode.

Needless to say, those wishing to posh out their iFi Pro kit have a matching micro stand to stack up whilst doing combat with physical micro resonances. May the stronger vibe lose.