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Considering this architecture one could see a stack of redundant gear: Data --> Cubox MPD --> filtered USB --> reclocker --> dac. After a bit of thought, it ends up looking most conventional digital processing chains: Max/PC --> software player --> USB audio interface --> dac. The relevant differences are: real-time processing in the Cubox; and replacing a standard USB transceiver with a reclocker for the filtered USB input. This entire chain is digital and each step seems designed to transmit the digital data in the best possible way to minimize all possible sources of jitter.


Auditions. With two DACs and a server, two amplifier/speaker combinations and two more sources, it became necessary to organize the listening sessions without testing all possible permutations to have sufficient time to do things right. I decided to focus on answering these questions:
  • iPad interface ergonomics since this is the first point of contact in a file-based music system
  • differences between the d1-tube and d1-dual decks
  • quality of the digital volume control for use without a separate preamp
  • what the d1-server adds over a direct USB connection to a PC.
And of course I’d make comparisons with my other sources. I figured that these were the main areas of curiosity an audiophile in search of a music streamer would want covered. For context we recall that my Ayon S5 to which the TotalDac would be compared was called the best PCM source in its prior 6moons review and was chosen as the reference network player by Stereoplay where it displaced the Linn which had ruled there for several years.



iPad control interface. We start here to maintain suspense and because it’s quite vital for any network player. For computer-phobic folks the easiest way to get music into the d1-server without a NAS is to plug a USB storage device filled with music files into it. Simply add an Ethernet cable between d1-server and router to enable the iPad and you’re all set. Unlike other systems, using a USB storage device retains tag-based control (by albums, artists, genres) to not be limited to folder navigation which can become painful as a library grows.


To use a NAS requires some minimal housekeeping chores. The NAS must be named totaldac-nas, the shared directory containing the music files must become music-nas. As much as possible, this simplifies things for the audiophile who will never need to deal with any Linux RT configuration shenanigans. Amongst the iPad, Android, PC and Mac platforms, I found the best control app to be the €2.69 MPad for the iPad. I also used the free MPDroid which seems to be the best Android app but which doesn’t allow album-cover navigation (it becomes complex with big libraries). I also tried the free Theremin app for Mac which is very basic but functional. These screen shots show the MPad GUI on my iPad.


The sorting/viewing options by album, artist, tracks and genre were very satisfactory. You can also navigate through directories should you have made tag errors or haven’t get inserted proper tags. The search function operates in all views and through tracks. Whenever you add tracks, the MPD server running on the d1-server must be updated in the MPad app by refreshing the local cover cache. Playlist handling was good and there’s access to last.fm and allmusic. The only possible issue with the MPad app is a lack of composer view which could be frustrating for classical listeners.



First impressions. The first impression of the d1-server + d1-tube was one of fluidity and musical immediacy. The music was simply present without any hardness or other faults. I started with a  24/192 PCM of Le Nozze di Figaro by Theodor Currentzis and ended up spending 3 hours listening to the entire opera. Rather a good sign. Over the next days I listened to all types of music and formats (PCM 16/44 to 24/192, DSD) and on both my systems from J.S. Bach to Michael Jackson via Bob Dylan and Mozart (perhaps my two favourites). Everything came off without any effort but great pleasure, sans fatigue or any apparent issues. As you know, reviewers are bound to search for problems. After these few days, the first word that suggested itself time and again was fluidity as that quality which is so difficult to obtain with digital playback; then clarity and air.


Switching to the d1-dual DAC to eliminate the output stage valve, I remained within the same aural aesthetic but the d1-dual added two items: more bass definition and a kind of weightiness across the entire soundstage. I’m aware that 'weightiness' is a bit vague. It’s neither better definition nor fuller timbres but a kind of heightened presence/substance without any hardness or counterbalancing issues. To keep it simple, it would perhaps be better and clearer to say that the d1-tube offered a bit less presence than the fully balanced machine. Practical differences were an output level of 1.4V for the d1-tube and 3.1V for the d1-dual. The d1-tube worked fine without preamp directly into my 40-watt Helios power amplifier whose input sensitivity is 650mV to drive the 92dB Pascal Louvet Isis speakers. Yet the same output voltage was insufficient to drive my 150-watt 1V Orpheus Lab 3M monos into my 86dB Sonus Faber Guarneri Evolution. Potential buyers of the d1-tube will thus have to consider their amplifier’s power and input sensitivity ratings, their speaker efficiency and the size of their room if they wish to eliminate a preamp. With its 3.1V output, the d1-dual will work with a far larger range of amplifiers, speakers and rooms in direct mode. After these first sessions I decided to focus on the d1-dual even if I still swapped between both DACs a bit to insure the differences didn’t exceed what I already described.