Perpetual Technologies P-1A D/D & P-3A D/A processors Upgrades
It's generally acknowledged by designers of audio equipment that the most reliable way to improve a product's performance without changing its basic circuitry is to improve the power supply. However, good power supplies are costly and not terribly glamorous, so manufacturers building products to meet certain price points often compromise in this area. Audio Alchemy's early digital processors were notorious for this, and the same seems to be true of the Perpetual Technologies products.
The P-3A's power supply is just a small transformer in a box; the P-1A has a switching power supply, a type that's prone to be noisy unless it's very sophisticated—which this one isn't. Perpetual Technologies appears to recognize that the stock power supplies may be the limiting factor in the performance of the P-1A/P-3A; they recommend the P3 Perpetual Power Plant ($349) from Monolithic Sound as an upgrade.
The P3, designed by ex-Audio Alchemy service manager Dusty Vawter, powers both Perpetual Technologies products and matches their cosmetics. It features a three-stage line filter, separate 2.5A low-output-impedance transformers, a full-wave bridge rectifier with four discrete ultrafast diodes, and the DC outputs have 10,000µF capacitance, bypassed by a high-quality Siemens metal-film capacitor. More to the point, the P-1A/P-3A combo sounds much better when powered by the P3 than by the standard power supplies—cleaner, more dynamic, better bass—so I would consider the P3 a mandatory option.
To a lesser extent, the same is true for the Mystic Reference I2S cable from Audio Magic. Perpetual's stock cable is not bad, and the P3 power supply makes a much greater difference than the change in cables, but substituting the Mystic Reference (silver-coated copper, extensive shielding, $149 for 0.5m) resulted in a slightly more extended, open treble.
I2S cables are still pretty rare; I checked the websites of AudioQuest, Kimber, and Monster Cable, and none lists an I2S cable. Perpetual Technologies is working with Audio Magic to come up with a cable that they can offer as an official upgrade. In the meantime, the Mystic Reference I2S allows for extracting another bit—meant not in a technical sense—of performance from the P-1A/P-3A. The Monolithic Sound P3 power supply and Audio Magic Mystic Reference I2S cable are available from the av123 website.—Robert Deutsch