I’m impressed. The BOLT offers fantastic build quality, MQA and THX certification, small size, high-power output, and clean and clear sound. What’s not to love? THX Certification is the icing on the cake here, meaning the BOLT has to meet stringent standards for low-distortion. Not only is it very affordable, but it delivers more than enough power for a lot of entry-level audiophile headphones and it sounds very pleasing in most desktop and entry-level systems. I know from some conversations with those who have measured the Helm Audio Bolt, that it delivers rather solid results on the bench and that everything I’m hearing from it with multiple headphones and loudspeakers is accurate.

Plugging in the Bolt DAC proved transformative. Even songs I was intimately familiar with sounded like listening for the first time. I found myself uncontrollably immersed in the music, drumming my fingers and tapping my toes along with the rhythm. Even to an untrained ear, I’d wager that the Bolt delivers a revitalizing experience. Should You Buy the Helm Audio Bolt DAC/AMP? Headphone output level automatically detects headphone impedance and sets level accordingly: 1V for < 150 ohms, 2V for >= 150 ohms, which corresponds to low gain and high gain. The device is plug and play, there are no Windows 10 drivers needed.I used a variety of headphones during my test period including the Oppo PM2 planar magnetic headphones, B&W PX, and Beyerdynamic Amiron Home; but my comments below will reflect my experience with the Focal Clear and B&W P9 Signature headphones. A slightly peculiar trait I’ve noticed with the Helm Bolt DAC is that it doesn’t always play audio when connected. Whether it’s a compatibility issue or the DAC not fully operating, I’m not sure. It has a mind of its own, working fine on some occasions or refusing to on others, the system recognising it as “ESS USB Audio” instead of “Helm MQA”. It can be very fussy.

That said, comparing the two is really comparing apples to oranges because they are basically two different things. The DB12 AAAMP is an analog-only device made to provide additional output power to devices that already sound good, like a DAP with low output power. On the other hand, the BOLT is made to improve the sound of devices with inferior DACs, like many smartphones.

The Bolt is not the bassiest dongle, which keeps the vocals up front. Midrange is clean and clear with a tinge of warmth. One of its biggest qualities is the very pleasant, well-rounded, smooth, appealing top end. It works well with most earphone/headphone signatures and, in particular, helps taming shouty ones.

The poor old Apple dongle is far flatter and dull-sounding in direct comparison. The BOLT’s low frequencies have greater authority and control. This is likely (at least partially) due to the BOLT’s far more robust amplification. User engagement and music enjoyment are heightened as a result. Unlike THX Onyx however, the amplifier portion of Bolt is not a THX AAA (Achromatic Audio Amplifier. Although HELM Bolt is THX certified for meeting the standard’s low noise and crosstalk requirements (THD+N%: 0.0008 at <150 Ohms, 0.0013 at >150 Ohms). For my sound test, I used the BOLT mainly with the Focal Elear headphone and a Moto G Fast Android phone with USB Audio Player PRO app installed. I listened to both TIDAL and local files thru UAPP, mostly hi-res.Over the past 19 months, 10 of these devices have landed in my mailbox and while it’s nice to have a wide selection of portable DACs to listen to with a lot of different headphones and desktop systems — I’m starting to feel that most of them sound very similar. I was ready to move on to something else but then the Helm Audio Bolt showed up and ruined my summer plans. Note: Open the Folder you will see three files Updater Utility exe., 0dB ROM (new firmware) file and the original firmware file. MQA (Master Quality Authenticated) promises the ultimate in audio fidelity. Like THX, the MQA company works with its audio hardware partners to design and certify their devices. MQA integration is still relatively rare, especially in portable DACs, so it’s exciting to find it in the BOLT.

And, honestly, there’s nothing wrong with that. Although, I did have to search through my shelf of boxes and pull out a few likely (and virtually identical) candidates before I found where I stashed the original box. I tested the power consumption of several portable headphone amps connected to my iPhone 5S. The conditions were as identical as possible: 3 h test, volume calibrated to 85 dB ± 0.5 dB white noise with Dayton microphone, no sim card, BT off, no other apps open; network on, 32 ohm Blon BL-03 iem, Genesis’s Supper’s Ready (from the Seconds Out album) played in an endless loop. The Helm Bolt is one such DAC. It’s small at only 95mm long and a width of 11.7mm, with a compact main housing that connects to USB-C input via a flexible cable. It’s much smaller than a comparable plug-and-play DAC like the Astell & Kern HC3.

Should You Buy the Helm Audio Bolt DAC/AMP?

The BOLT offers clarity and impact that many other tiny DAC/amp dongles are missing. This picture is simply a size comparison between the BOLT and the Lightning-to-3.5mm dongle. Any resemblance to a smiley face is entirely coincidental and, to be honest, rather juvenile. Where to Buy The Helm Bolt has an LED indicator to show you the signal format and sampling rate. Magenta indicates the presence of an MQA signal. A revelatory listening experience Thanks to DB12’s 4-pin TRRS connectors you can talk to your phone if your headphones or IEMs are equipped with a mic, even when DB12 is powered off. The amp has a passive bypass mode that provides continuity from your source to your headphones. So, even if DB12’s battery is drained or shutdown, you still have use of your headphones, including mic, albeit at lower volume. Regardless of what all that means on a technical level, it is fair to assume that THX certification is a good thing. It serves as an indicator of quality assurance and a high standard of performance. Amplification WORKS WITH Android, iOS, MacOS and Windows 10 via USB-C Input and 3.5mm Headphone Output *iOS requires a Lightning to USB Camera Adapter