Because the Antipodes Oladra, like music library/reclocker/server solutions from Melco, Aurender, Auralic, Innuos and others, is a data-storage and -delivery device, any technical or subjective uplift in performance—over a conventional NAS or PC/Mac USB solution—can only be inferred via an attached, third-party streaming player or DAC. Identifying any reduction in jitter or circulating RF interference from the Oladra also depends on the efficacy of the USB receiver's jitter suppression and/or galvanic isolation; a USB DAC with excellent data recovery/reclocking may not express a significant difference.
Similarly, any DAC solution with its own baked-in sources of jitter that arise after the input interface will suffer the same phase/amplitude-modulation sidebands in the analog domain regardless of the coherence of the source's digital data. Ironically, the more rudimentary USB hub-powered DAC/headphone amplifier solutions—as opposed to high-end USB DACs with integral power supplies, etc.—provide the best indicator of incoming data integrity and noise (or lack of it) on the +5V supply.
AudioQuest's original DragonFly DAC (fig.1) illustrates this perfectly, for while there's a worthy reduction in correlated jitter from 300ps (desktop PC, USB source) to 120ps (Oladra source) it's the approximate 95% suppression of circulating interference (spuriae), and the improvement in A-weighted S/N from 94dB to 104dB, that will surely have the biggest subjective impact.
A significant cleaning up was also realized with iFi Audio's NEO iDSD, where the 550ps of ±33/66/99Hz sidebands collapsed to just 10ps (fig.2) with Antipodes' Oladra as the USB source. Otherwise, there is no change in the NEO iDSD's 4.29V peak output, minimum 0.00015% THD (ref. 1kHz/–10dBFs) or, despite the 2dB "step" reduction in HF noise, its 109.7dB A-weighted S/N ratio. (iFi Audio has improved its input jitter reduction at source in its more recent NEO Stream DAC; review forthcoming.)
Other USB DACs tested, including the Mytek Brooklyn (fig.3) and dCS Vivaldi One Apex, have sufficient galvanic isolation/onboard reclocking that very little difference in jitter was observed between the PC and Oladra USB sources. Variations of a mere ±1–2ps were measured, although there is still a visible reduction in the finest spuriae (red spectrum, fig.3). Arguably, every little helps.—Paul Miller
