In the summer of 2021, MoFi Distribution's Jonathan Derda emailed me about the South Korean HiFi Rose brand. "This brand strikes me as being the spiritual successor to the original SlimDevices Transporter and Squeezebox Touch," he wrote. "We're all really excited about it."
I bought a Wi-Ficonnected Slim Devices Squeezebox at the beginning of 2006, to experiment with streaming. When Slim Devices released the high-performance Transporter, I was sufficiently impressed that I purchased the review sample after measuring it for Wes Phillips's review in the February 2007 issue. I used the Transporter for several years,but after Logitech, which had purchased Slim Devices at the end of 2006, stopped supporting the Squeezebox devices, I put it aside. By that time, I had started using the Pure Music and Audirvana streaming apps, which I preferred to Slim Devices' SlimServer software (footnote 1). But every few months, I fire up the Transporter, feed it audio data over my network, and spend a nostalgic evening enjoying what it does.
Given that history, it should come as no surprise that I eagerly agreed to review HiFi Rose's RS250 Roon Ready, streaming D/A preamplifier.
Priced at $2495, this is a relatively small device, its front panel dominated by a large four-color touchscreen display almost 9" wide. To the screen's right are the standby button, a volume control knob, and a 3.5mm headphone jack. By contrast, the rear panel is crowded, by a pair of single-ended analog inputs and several digital inputs: coaxial and TosLink S/PDIF; USB Type B for connecting to the USB output of a PC or similar; USB 3.0 Type A for connecting to a storage device; and an Ethernet network port. The RS250 has one pair of single-ended analog outputs and three digital audio outputs: coaxial and optical S/PDIF and USB Type A. A video output, with a resolution up to 3840 × 2160 at 60Hz, is available on an HDMI 2.0 port. AC power connects to a 15A IEC jack. In addition to these wired connections, the RS250 does Airplay, DLNA, Roon, Spotify Connect, Tidal, Qobuz, and other streaming services.
Internally, two ARM Cortex 64-bit processorsa dual-core Cortex-A72 and a quad-core Cortex-A53 with 4GB RAMrun the Android 7.1 operating system. The power supply is linear rather than switch-mode and features a configuration said to minimize electrical noise. The analog output stage features the relatively new ESS ES9038Q2M two-channel DAC chip, which has what is described as a "Femto Clock." Internal SSD data storage is an optional extra; this was not fitted to the review sample.
That screen is what makes the RS250 both noteworthy and useful. When the unit is turned on for the first time, it prompts you to enter your time zone, country, and preferred language. After that, a horizontal stream of icons is displayed. There are so many icons that you need to scroll left or right to see them all. Some are self-explanatoryMusic, Video, Qobuz, Tidal, Clock, Settings, In-Out Settingwhile others are enigmatic: Bugs, RoseFM, RosePodcast, RoseRadio, RoseStore, RoseTube, CD Play, and CD Ripping. (The RS250 doesn't have a CD drive.)
Pressing the Settings icon allows you to adjust things like the display brightness, the format of the clock display, the appearance of the VU meters that appear when music is playing, and rearrange the order of the icons. You can also check the operating system version and IP address, connect to a Wi-Fi network, and watch a tutorial video. An In-Out Setting icon allows you to choose an external input, digital or analog, set the input to Internal, where it defaults to the network input, and choose a digital or analog output. When you select the analog outputs, a gearwheel icon appears and allows you to choose one of seven FIR Interpolation reconstruction filters (see the "Measurements" sidebar); select variable output level or one of eight fixed output levels ranging from 100mV to 2.2V; resample the incoming digital data (choices are from 44.1kHz to 192kHz) or not; invert polarity; and apply correction for the bottom 8 bits with 32-bit audio sources.
Setup and use
When I first turned on the RS250 and connected it to my network by Ethernet, it assigned itself an IP address then told me that it needed to update its operating system. This it did, and the front-panel display identified the system as "3.8.13" and the audio firmware version as "XMOS 3115." I then set the time, my language, and my country.
Roon recognized the network-connected HiFi Rose as an endpoint; I also connected the RS250's USB Type B input port to the USB Type A slot on the back of my Roon Nucleus+. When I selected the USB input with the RS250's In-Out Setting icon, Roon recognized it as an ALSA device. For CD playback, I connected an MBL N31 player's optical output to the RS250's TosLink input with a 1m length of AudioQuest OptiLink 5 cable. I learned that the RS250's animated front-panel meters don't function with the S/PDIF and USB connection, nor is the file's metadata displayed with USB data as it is with the network connection or with playback from an external memory device.
I mainly used the RS250's single-ended analog outputs connected directly to the Parasound monoblocks, those in turn connected first to the PSB Synchrony T600 loudspeakers I reviewed in November, then to the GoldenEar BRXes. Playback volume could be adjusted with Roon's level control (network and USB) or with the front-panel knob or Bluetooth-connected remote control (analog and S/PDIF inputs and local media). Mostly, however, I used the RoseConnect Premium app (v3.04.27) from the comfort of my listening chair. This app requires iOS 13.0 or later, and my older iPad Mini runs iOS 12.5.4, so I installed RoseConnect Premium on my iPhone 11, which was running iOS 14.8. The RS250 was identified as "ROSE 5-D." I used the app to log in to my Qobuz and Tidal accounts, and the Tidal and Qobuz albums I had previously added to my Roon Library appeared in the Tidal and Qobuz album windows, both in the app and in the RS250's front-panel display.
Some audio settings, I learned, are available only via the In-Out Setting icon on the front-panel display and then the gearwheel icon mentioned earlier. Based on my experience with the reconstruction filter settings with other D/A processors that use ESS Sabre DAC chips (footnote 2), I selected the "Corrected minimum phase Fast Roll-off" filter (see "Measurements" sidebar) and set the RS250 to play files at the original sample rates rather than upsample them. I don't have any 32-bit audio files, so I left "Lower 8-bit correction for 32 bit sound source" switched off.
A Menu item allows the RS250 to access a music library stored on a NAS network drive. However, as my NAS is currently offline, I plugged a 16GB USB stick carrying some reference recordings into the USB 3.0 "In" port on the RS250's back panel. The RS250 recognized the storage device and asked if I wanted to scan the contents and create a database. Once this was done, after a delay the albums appeared in the app's and front panel's Music window. There was also an MPEG video file on the USB stick, and I could play this with the RS250, the video image appearing on the front-panel display. Selecting RoseTube with the app or display brought up a selection of music videos on YouTube. Similarly, selecting Radio and (in response to a prompt) selecting "USA" as my country brought up a list of internet radio stations.
Footnote 1: Now called Logitech Media Server, this open-source app is still being regularly updated. It can be used with servers like the Antipodes K50 that Jason Victor Serinus reviewed in the November 2021 issue.
Footnote 2: See for example, the discussion of the filters in my review of the Okto dac8 Stereo.