HELM Audio Bolt DAC/AMP, USB-C Portable High-End DAC/Headphone Amplifier with MQA Playback. Mobile Studio Sound for Android, iOS and PC. USB-C to 3.5mm Audio, THX Certified

I bought this on the basis of the Hi Fi World review done by Noel Keywood. His report on it's sound quality and usability combined with his comments on the Sabre ESS dac convinced me. Also, the price is stunning for the product. As a Pixel phone user, the Apple issue was irrelevant to me. Although there are reports of a running in period, I spent time on Spotify playlist and the hi Res digital file of Moving Pictures by Rush I bought from HD Tracks..It is short, strong and was no inconvenience attached to my phone. Thoroughly recommended, but I recognise it has strong competition in that price range.

I liked the simplicity and size of this unit which I wanted to use with an Android phone - it is perfect in that respect. In addition, I found that the device was indeed every bit as good as the reviews claimed - the sound is open and spacious, clear and smooth and has a very good sound stage and an overall neutral sound. I wanted to try DSF files via Android from my home server which I was successfully able to achieve. Full marks to the combination of the Helm and USB Audio Player PRO in achieving this objective. On a further note, my first Helm device very intermittently exhibited a cracking sound (tricky to pinpoint for a while) and the Helm service was excellent in sending a replacement - the replacement is perfect so I do highly commend not just the product but also the aftersales service! First class all round.

My initial impressions were good. It seems expensive for what it is (though on a par for similar-type products), but comes in superior packaging and a nice quality feeling carry case. The only slight concern I had was that when inserting the headphones there was some give and movement in the headphone jack. I assumed this was to give some slight ‘suspension’ and relief, but as things turned out may suggest that it was a faulty unit.Initially it worked very well. Plugging into iPad, phone and laptop all worked with plug and play ease. The sound is clear, has some weight and plenty of detail. Definitely a step up on an Apple headphone dongle. The only cautionary note was that I found when it was paired with bright-sounding headphones the sound could get a little fatiguing.However, after a week or so I started to find that it would have to be plugged in, removed and then re-plugged before it would work. Then a few days later it stopped working altogether. Although my iPad and phone would both recognise that the DAC was present there was no sound. No choice but to return it as faulty.

This is a really cool device to improve the quality of my sennheiser momentum 2 headphones with my iPad pro or Samsung note 10. This is not much bigger than the basic USB to headphone adaptor from Samsung or Apple so it's incredible because it takes up no more space than what I was already using.Only reason I'm giving it 4 and not 5 stars is because the sheath has started coming away from the connector after just 2 weeks use. Not sure if it'll lead to it becoming faulty but returning it for a replacement just in case.When using on my Samsung phone it is a massive upgrade from using the Samsung adaptor. My headphones sound so much more present with the mid-range really stepping forward and all the other instruments gaming much more clarity and the bass gaining incredible amounts of depth.The upgrade is more subtle on my iPad Pro and MacBook Pro so I assume the Apple usb-c to headphone adaptor is better than my Samsung one and the Mac internal DAC is clearly very good and nearly comparable to this, however with the iPad the improvement is still very noticeable with instruments really stepping forward and gaining much more presence.it's interesting because my sennheiser headphones MOMENTUM 2 get really great reviews even over Bluetooth when in reality compared to using it with this DAC they sound flat and distanct. So the sennheiser momentum 2 are clearly massively restricted when using them via bluetooth compared to using them via this DAC and I'm delighted I bought it.Highly recommended!!!

(Updated review)After about 10 months mine stopped working, but before that, I started to notice some issues like lose USB c connection, it was very very easy to detach and lose audio, One day out of the blue, nothing!! just stopped. I got a blue light and there was apparently power in the unit but no audio, and my devices won't recognize it anymore.( Original review down )Ok so I have many dongles, dragon fly red, hidiz sonata, shanling, Fio amplifier, this one is by far the best in terms of clarity, have Grados RS2E, Yamaha Mt220, Fidelio, X2hR, and the very pricey Meze Empyrean that am just testing ( not mine)I have to say this DAC SLAPS!! Very well defined sound stage very clean clear sound coming from the dac, hook it to a laptop,or ohone. All my headphones have a diff sound signature and so far the ones I like the best with this dac are the Grados and the Fidelios. ( I think because the dac is on the brighter side of sound)Rock music: like ZZ Tops, America, Fleetwood Mac.Jazz as: slowly rolling camera, Miles davis, Daniel Herskedal.Sound freaking GREAT!! really good for a portable dongle dac.Hopefully it will keep working longer and by the way I can't tell the difference when paying mqa files and other files seems to me like more of a gimmick than actually something special, but that's me.