The HELM Bolt is a $99 portable, THX-certified, MQA-capable USB-C DAC and headphone amplifier. Once connected to a smartphone or laptop, the Bolt will pull digital audio from the host device and convert it to analogue using its own onboard circuitry, thus bypassing the smartphone or laptop’s internal DAC and headphone amplifier.
That means a one stip click-clunk for Macbook and Android devices but iPhone users will need a Lightning-to-USB adapter and a USB-A to USB-C adapter. (The day that Apple cuts its iPhones over to USB-C cannot come soon enough).
Things get a little confusing when we examine the Bolt’s hi-res audio capabilities. The press release claims support for sample rates up to 96kHz but is contradicted by the HELM website that indicates the Bolt can handle PCM up to 384kHz. What gives?
A quick phone call to my MQA contact extracted the following information: the Bolt works in the same way as AudioQuest’s DragonFlys, where the software (Tidal, UAPP) executes the first unfold (to either 88.2kHz or 96kHz) in order to slip underneath the Bolt’s 96kHz USB receiver chip ceiling. Once the first-unfolded signal reaches the DAC chip, all subsequent unfolds are carried out and MQA rendering executed. If he’s right, all streams coming from services that don’t use MQA to deliver hi-res audio will be capped at 96kHz.
The HELM press release is also a little hazy on exactly which performance parameters were met for their dongle to claim THX Certification. HELM’s website states “Ultra-Low Harmonic Crosstalk & Reduced Crossover Distortion”. Perhaps that’s it? Or maybe the details contained in this image point the way:
On a more fundamental level, the Bolt’s primary intent is to better the sound quality of a laptop or smartphone’s 3.5mm headphone output (should it have one). That makes the HELM dongle not just a good idea for hi-res audio but for all audio, including the CD-quality streams that remain the bread and butter of Qobuz and Tidal’s hi-fi tiers and the lossy streams that spill from Spotify and Apple Music. Yes, a DAC like this will improve the sound of Apple Music and Spotify!
Further information: HELM