Sometimes big things start with a throwaway line.
We were deep in development on our upcoming reference DAC, the PMG Signature 512, working out the particulars every new technology demands: power supplies, interface challenges, and voicing the system. After a particularly satisfying listening session, loudspeaker engineer Chris Brunhaver casually asked me, “Why don’t we ditch the digital volume control and go with an analog stepped attenuator instead?”
Say what?
Everyone uses digital volume controls. It’s what DACs have done for years. The MKI and the MKII, like 99.99% of all high-end DACs on the market (not to mention every single DAC we've ever built since 1985), control the output level of our products digitally. You change the level in the digital domain losslessly using math, attenuation algorithms, and dither. It's perfect!
Yet…the idea gnawed at me.
Chris wasn’t talking about just swapping one part for another. He was suggesting a major architectural change: rebuild the DAC's digital architecture to operate at full output, unattenuated, and do the volume control using an analog stepped attenuator like you might find in a high-end analog preamplifier.
Radical.
When you digitally lower volume, you don’t lower noise or distortion. You’re just shrinking the signal. The noise stays the same. The distortion stays the same. But the music gets smaller. It's like making a photo darker by turning down the brightness on a projector instead of dimming the room.
For folks using a separate preamp, it doesn’t matter. But if you’re going DAC-direct into a power amp? It matters—a lot.
Chris' throwaway line stuck with me like a catchy song I couldn’t get out of my head.
And the more I thought about it, the more it made sense.
To be continued.
