Network Audio Players/Servers

This new trickledown player/DAC represents a distillation of the second-gen DPC (Digital Processing Core) debuted in HiFi Rose’s RD160 USB DAC [HFN Jan ’25] and RS151 [HFN Jul ’25]. That last music library/streamer also marked a departure from the AK4191EQ upsampling/noise-shaper and AK4499EXEQ DAC employed previously, exchanged for an ES9039SPRO DAC from ESS. In the RS451 we now see a sideways move in HiFi Rose’s use of two ES9027SPRO DACs, one in the main line output, the other feeding the separate headphone amplifier stage. Importantly, the software and CPU ‘engine’ have been retained, the RS451 also featuring an 8-core RK3588 processor from Rockchip, with DRAM increased over the first-gen models from 4GB to 8GB and local eMMC storage from 8GB to 32GB.

HiFi Rose’s digital signal routing utilises what it describes as ‘Femto clock synchronisation and I²S signal alignment’ to suppress jitter and signal distortion. The Inter-IC Sound (I²S) protocol was developed by Philips in the mid-1980s as a method of transmitting two-channel LPCM from chip-to-chip as separate clock and serial audio data lines. Some hi-fi brands, including PS Audio, Matrix Audio, Mola Mola and Eversolo, use an I²S bus to send data between a disc/streaming transport and outboard DAC, maintaining synchronisation and avoiding the need for clock recovery in the destination device.

That said, as before, the LPCM/DSD upsampling, digital filter and volume code is restored to the Rose DPC every time a change is made in the ‘Output Settings’ menu and the ‘Apply’ button is pressed. Music playing back from connected media is interrupted and paused at this time, though streams being ‘pushed’ to the RS451 via coax, optical or USB-B resume after a few seconds. HiFi Rose offers a comprehensive digital manipulation toolkit in the RS451 but not all the functions appeared to execute reliably when changes were applied from the menu [see PM's Lab Report]. The brand is not alone in this regard [see HFN Dec ’23 and Feb ’25] but other streamer/DAC solutions do offer swift and reliable resampling and digital filter changes on-the-fly. PM