A few issues ago (Issue 163 to be specific), I was wowed by the excellent I35 from Primare. We deliberately chose the denuded version (without its clever Prisma media renderer platform) because we wanted to see how good the amp is on its own, without being clouded by the prism of Prisma. So, we have waited until the newer, smaller I25 emerged, so we can tick three boxes at once – how the I25 performs in and of itself, how it compares to the I35, and how Prisma works.
Short answer, all three boxes are firmly ticked, and ticked well!
Let’s work in that order. The Primare I25 amplifier platform is a 100W integrated design, featuring the companies own UFPD 2 amplifier modules, an updated version of Primare’s original ‘all-analogue Class D’ UFPD module. And let’s stop almost immediately: there’s a sort of myth in audio that the ‘D’ in ‘Class D’ stands for ‘digital’. Class D refers to using the amplifying devices as high-speed switches instead of linear-gain devices as in Class A or Class AB amplifier designs. The confusion comes from the fact that Class D amplifiers create an audio signal by passing a pulse-width modulation output waveform through a low pass filter, “and PWM is digital, therefore... digital!” However, there is no analogue-to-digital or digital-to-analogue conversion taking place within these UFPD 2 amplifier modules. None at all. And yet, the ‘D for digital’ meme hangs around the industry like a fart in a camper van. I suspect it’s because at least some of the ‘D for digital’ carney barkers are finding a convenient if functionally meaningless sound-bite to universally bash Class D, without the inconvenience of having to listen to any amplifiers first!
On its own, the I25 features five line-level inputs and two outputs, alongside some sync/trigger and RS232 inputs for multi-room use. That’s a good starting place, but things quickly escalate.
There are two upgrade modules, which can – and in most cases, ‘will’ – be fitted in the factory as the I25 rolls off the line, or as after-sale plug-in modules. The first is the DAC module, which adds USB and S/PDIF connections (mostly Toslink) and sports an AKM AK4497 converter chip. The second (which requires the DAC module to also be in place), is the Prisma module, and it is where things get really interesting.
Prisma is the digital streaming platform common to Primare products. It runs on a Google Chromecast backbone, but is pretty much platform agnostic; you can connect it via Ethernet to a local network and/or the internet (it talks to UPnP devices in the home and to systems like Spotify Connect or Tidal out there in the big wide world). Chromecast also makes the I25 Roon-chummy.