Furutech ADL Stratos DAC with Headphone Amplifier

UPDATEI have an old Marantz cd4000, which cost me about £30, 20-odd years ago. (On sale in Dixons). Although an "entry-level" cd player, it still has Marantz quality. Basic but decent sound, good quality drive mechanism.It has a co-ax digital output for use with an external DAC, and connected to the Furutech Stratos via a Cambridge Audio co-ax connector, it has a much superior sound, It doesn't make the Marantz into a giant-killer, but I'd say it's as good as a £300 cd player. Good, solid, tuneful bass, smooth mid-and treble sound, lots more detail, wider and deeper soundstage, and a good amount of dynamics, giving a solid "whack" to percussion for rock and jazz. Altogether a more solid and clearer sound than the stock Marantz.I compared the sound of the Marantz via the normal analogue outputs and via the Furutech, through the same amp and speakers.ORIGINAL REVIEW;I have had this unit for only two weeks, and I am very impressed. The sound is excellent; dynamic, with deep, well-defined and well-controlled bass; smooth, clear midrange with no trace of harshness, and clear, bright but smooth treble. When midrange and treble are well-presented like this, it's a sign of properly designed and executed digital sound, no trace of harshness. It makes my old Sony headphones (£10 from Dixons about 25 years ago) sound their best, so my next investment will be a pair of better headphones to do justice to the Stratos. I also will get a co-ax digital cable to connect my old cd player to the Stratos, to see if it can bring out the best sound from that too.It is also a good pre-amp, I have it connected to an amplifier via phono connectors, and it provides the same clear dynamic sound.I am using this with a USB connector (supplied with the unit) to my desktop pc, whose operating system is Linux Mint 18.3 with Cinnamon desktop. The unit works straight away, just plug-and-play, but I had to change a line in the Pulseaudio configuration to make sure the computer always plays back at 48000 sample rate, this is to do with Linux Pulseaudio, and not a fault with the Stratos.A nice touch is that when restoring power after being muted or on standby, the volume defaults to zero, and then is automatically raised to its previous setting.The remote is very useful, and small - imagine a stack of about 15 playing cards - so it doesn't take up too much room on your computer desk.I haven't used the phono or line inputs yet, so I can't comment, but they will enable you to archive your old vinyl records before they wear out, or cassette tapes before they fall to bits!I am giving the Stratos 5 stars on its performance as a DAC/headphone amp.The build quality is excellent, but I would prefer a firmer feeling power button, it's not actually bad, it's a plastic button with a spring behind it, and would feel better if it was a soft-touch type, as on the remote control. That's the only slightly negative comment I have, and even then it's a personal preference and not an actual fault.Very well pleased with the Stratos, highly recommended if you want a headphone amp, DAC, pre-amp, and phono stage all in one box, with excellent audio quality, to get the best sound from a computer.