Audioengine32-bit D1 Portable Desktop Headphone Amp and DAC, Preamp, USB/Optical Inputs, Hi-Res Audio Playback (2nd Gen)

My Audioengine D1 USB / optical / DAC was delivered and works exactly as I expected. I am very pleased so far. It has a good air of "quality manufacture and robust construction". It is very easy and logical to use, and the performance / sound quality is very good with no noise. I have experimented, trying to "catch it out" and very occasionally after unplugging and re-plugging the supplied USB cable (between laptop and D1), I have encountered mild "playback stutters", but turning power off (the button on the D1), then back on, always seems to overcome the problem. I can now play all my mp3 collection from my Toshiba Laptop (ripped from my CD collection at the highest bit rate allowed by the Microsoft Software). My “HiFi” speakers are either side of my TV, so I can also play sound from "Youtube" and “catch-up TV” from the Toshiba through them from my laptop to accompany watching their pictures via hdmi. The sound quality from both "Youtube" and “catch-up TV” is very good. "Plug and play" with the D1 so far works seamlessly on my laptop with MS Windows 8.1. The power button LED is bright (white), but because of the cabling, it faces away from me so I don't see it (hence the dim glow is good for letting me know if the unit is "powered up"). The D1 "on-off power button" is actually very convenient, as is the "volume" knob (during play of, for example, an mp3, if the D1 is switched off using its "on-off power button", the music is then automatically switched to the laptop's speakers, then on re-powering the D1, the laptop speakers are switched off, and the output to my "HiFi" speakers is gently re-applied). The operation has exactly the logic I would expect. BACKGROUND TO MY REQUIREMENT: I was happy enough using an old Dell laptop PC as an mp3 player via its internal (DAC) sound card through my Cambridge analogue amp and some old "Acoustic Research" speakers (my entire ripped CD collection is on the Dell hard drive). However, the Dell battery failed, so I can now only run it from the mains power supply and the noise pick up from the analogue cables was terrible (I had the cables connected to the headphone output on the Dell). I have all the same mp3 files on the hard drive of my Toshiba laptop, but for an unknown reason, I got nothing when I tried to drive my Cambridge amplifier from the headphone output on the Toshiba. By contrast, the D1 is powered from a USB connection with the laptop (no internal rechargeable battery), and uses the USB as the digital source, hence, I can use it on either my old Dell laptop or my Toshiba laptop. The D1 does have a headphone amp, but no balance or frequency controls (only headphone output adjustment via the D1 knob). But the main reason I wanted the D1 was for its stereo-phono outputs to connect my existing analogue cables to my Cambridge amplifier. My Cambridge amplifier then gives very good gain / balance / frequency control. The D1 gives me future options for use of USB or optical inputs.

It's best that I explain at once that I am a composer (classical) and recordist of natural soundscapes, so the term 'audiophile' does not describe me precisely enough; I'm used to listening into the nature of sounds in a very analytical way as well as aesthetically, and wanting them reproduced accurately rather than necessarily pleasingly. I am particularly fussy about getting full but **accurate** reproduction of lower bass frequencies, which usually falls at least to some extent by the wayside from most 'consumer' speaker systems - subwoofer systems all too readily resulting in misshapen and usually exaggerated or boomy bass.I'd read many user reviews of the D1, which claimed that it had greatly improved the sound that its users were getting from their speakers, but I still expected really only subtle improvements - especially as for a week or two up to that point my Audioengine A2+ speakers had been connected to my computer via USB, which meant they were already getting the advantages of an external digital / analogue conversion (DAC), and I'd noticed only small improvements over the sound I'd had from the speakers connected to the analogue Line Out connection from the computer. Indeed, I was wondering if therefore I would really notice any further improvement at all with the D1 connected.These speakers had progressively 'opened up' during their breaking-in process (most likely not yet completed), giving ever more audible reproduction of the very low frequencies - i.e. those below the 60Hz given as the official bottom-of-range for that model, right down to the limits of hearing. Yes, I could actually hear 30Hz, and even a hint of 25Hz (which latter is at the limit of my hearing range now anyway). However, they were still a fair way from emulating the effortless room-filling very low bass that I routinely get from my Castle Harlech floor-standers. In the case of the A2+ speakers, normally I did need to concentrate a little really to hear those lower frequencies, even while I was sitting at my computer, with those speakers closely facing me, placed under either end of my monitor, which only just clears them (on its custom-made plinth) - and when I retreated at all into the room at large I had to concentrate even more to notice those very low frequencies.Then, enter the D1, and, at a stroke I was hearing EVERYTHING, right down to below 30Hz, without having to concentrate. Also, when I got away from the computer, into the room at large, I found that those low frequencies were being projected right out. My musical listening tests at this point were all classical recordings - Messiaen's Messe de la Pentecôte and Livre d'Orgue in Beauvais Cathedral, Havergal Brian's gargantuan Gothic Symphony in the breathtaking Martyn Brabbins recording, and various of my own compositions in life-like MIDI realizations - and I also listened to a range of natural soundscape recordings of mine. The latter, however, showed that I still hadn't fully got the sort of very low bass rendering that I routinely get with the Castle Harlechs or indeed my Sony MDR-V6 headphones, but of course even technological 'miracles' can go only so far for such small speakers! Still, I was routinely hearing the fundamental tones of low double bass and organ pedal notes, so I was definitely 'awestruck' (to use a cliché) at the considerable sound upgrade that I'd almost unwittingly brought upon myself.All that, together with a greater general clarity, and, apparently, some increase in dynamic range, has made for a remarkably natural and life-like sound for any pair of cabinet-enclosed cone-based speaker systems, and really phenomenal for a pair this small - particularly for music listening. As already intimated, though, for natural soundscape recordings, especially of sea doing interesting things, one would need either larger speakers or a suitable subwoofer carefully configured. Nonetheless, the D1 has had a dramatic totally positive effect on the sound that I'm getting.Listening through my headphones, which are extremely 'analytical' in their sound, actually the improvements make some material - especially my natural soundscape recordings - sound a bit more unnatural. That is NOT because the D1 has done anything bad, but rather, the improvements in clarity have caused the sound to show up even more clearly the unnatural effect of listening to the particular recordings through headphones. What is actually needed to rectify this is some sort of adjustable cross-mixing utility between headphones and source. Audioengine could do future customers a favour by incorporating such a facility in a future, upgraded version of the D1, or, conceivably, producing a separate device to put between the D1 and headphones.Now for the odd small niggles. It's great that there is a level control for the headphones, but it is also the level control for the output to the speakers. So, depending on the sensitivity of your headphones, like me you might need to have a volume control inserted between the D1 and the headphones so that you can get the right volume when playback through the speakers is at the right level for you, for it doesn't make sense to have to keep twiddling the level control each time you switch between headphones and speakers. Also, of all silly things, the level control knob has no markings at all, so you cannot see the level that it is currently set at - a very unhelpful omission. I have placed the requisite mark on the knob myself.And finally, I do wish that manufacturers / designers would let go of their extremely unhealthy preoccupation with black as the apparently mandatory colour for so many of their products - especially anything electronic these days. It is not only ugly to any genuinely healthy mind, but labels and other text on black backgrounds are generally difficult to read or even see, and a lot of black in one's living space absorbs significant amounts of light, so darkening one's abode, which is unhealthy psychologically and thus eventually physically too.

The device definately improved the sound quality. A pair of Creative speakers sounded far lot better through the Audioengine device than connected directly to laptops 3,5 mm socket.The slight downside is that there is not possible to change the sound - no equalizer or any other kind of adjustment. I have a pair of quite decent headphones and when connecting those everything sounds just so... dull. Clean and perfect but just dull.All in all - good device.