Sometimes I just don’t know. It happens with wine all the time, when I’m only sure it’s good if I know the price. And so it is, to an extent, with hi-fi. With headphones and speakers I’m confident I can hear quality, and I nearly always find my judgement borne out by the specialist critics. But ask me to judge one amplifier against another, or a CD or vinyl deck, or, heaven forbid, speaker cables, and I, well, just don’t know. I do wonder if the critics could really tell one from another in blind trials.

So to this beautifully made and critically acclaimed new Arcam rPAC portable DAC (digital to analogue converter), which, it is argued, will bring serious high-end-hi-fi quality to the music files on your laptop or desktop by bypassing the internal amplifier and processing and amplifying them itself – given that you have good portable headphones, such as the new B&W model.

Thing is (and I’m going to be brutally honest here, even if it makes the hi-fi lobby snigger), when I first tried it – note that I’m saying first here – it seemed to do little more than make the music sound muffled. I listened and listened for hours. I found one specialist review that read: “Play the Red Hot Chili Peppers’ Can’t Stop and the impression of depth and spaciousness around vocals and instruments is superb. The transparency on offer makes for an extremely detailed and insightful sound. There’s a real sense of immediacy and snap to each snare-drum thwack, and the rPAC delivers plenty of weight too.”

So I played it. Again and again and again. For hours. And, I have to say, the critic is right. You need to listen hard, but eventually the difference is not only detectable, the rPAC version is far preferable. The rPAC-ed music still needed adjusting to get it right for my ears – there’s a hidden equaliser in iTunes under the Window tab that I’ve used to boost the treble a tad. That done, there’s no doubt that this tiny, 300g device – which is USB-powered so needs no batteries or power lead – is perfect for office desk or business trip. Do persevere with it, and I think you’ll agree.