The Hidizs S3 Pro is a digital-to-analog converter and amplifier (DAC/AMP) combination unit in a dongle form factor. It has a 3.5mm single-ended output. The S3 Pro retails for $69.99 at HiFiGo. HiFiGo provided me with the S3 Pro in exchange for my impressions.
PACKAGING AND ACCESSORIES:
The Hidizs S3 Pro comes in a small black square plastic case with a black slipcover. The front of the slipcover is illustrated with the S3 Pro and is branded with the Hi-Res Audio, DSD, and MQA logos in addition to the Hidizs logo. Technical specifications for the S3 Pro are provided on the rear of the slipcover in English and Chinese. In addition to the device itself, the package includes a user manual, a warranty claim card, a quality control pass chit, a 10% discount coupon for the Hidizs online store, two extra Hi-Res audio stickers, and a USB-C female to USB-A male adapter. This adapter does not have active circuitry to prevent back-powering and I do not recommend using it.
The Hidizs S3 Pro seems average in terms of its power delivery compared to similar devices but is more than capable of powering any IEM. Achieving my testing volume with the Moondrop S8 required a 32% system volume setting in Android.
The S3 Pro’s implementation of the Android 3.5 mm Headset Accessory Specification is incomplete. I tested the S3 Pro with two different microphone-enabled cables. With a generic KZ cable and the cable from the Kinera BD005, the S3 Pro registered a short press as play/pause, double press as next track, triple press as previous track, but it did not register long press as the trigger for voice assistant. It treated a long press the same as a short press. With the KZ cable, the Apple dongle registered the headset accessory control functions correctly according to Android specifications (Play/pause/hook (Short Press), Trigger Assist (Long Press), Next (Double Press)). I also tested the BD005 cable with the Apple dongle and could not get my phone to register any mic button inputs. Your experience may vary depending on how your cable is wired.
However, one core piece of functionality of a dongle-style DAC/AMP which was consistently broken across all the IEMs I used with the S3 Pro was the pause on disconnect behavior. The S3 Pro does not pause playback when headphones are disconnected under any circumstances, though it does pause playback when the S3 Pro itself is disconnected. While this behavior is tolerable from devices that are largely intended to be used as external sound cards for a laptop or personal computer, I find this unacceptable in a dongle intended for portable use.
The Hidizs S3 Pro has an average power draw compared to similar devices.
There is not much difference between the power consumption while in use as compared to idle. There does not appear to be a power-saving mode or auto-shutoff function.
In terms of sound quality, the Hidizs S3 Pro falls into the broad bucket of adequate. It sounds as uncolored and clean as I would expect any competently designed generic source device of its price to sound. It also lacks any real distinguishing characteristics in terms of its intangibles or transient delivery.
I find it difficult to get excited about the Hidizs S3 Pro. This is not an indictment of the S3 Pro specifically, but of the broader audiophile dongle ecosystem. There are a lot of very similar devices on the market at this price point which do little to stand out from each other. I would love to see more innovation in this space, either in terms of additional functionality or major improvements in power efficiency.
The S3 Pro also comes with significant functionality limitations with respect to portable use. I continually experience the same issues with Hidizs devices regarding their compliance with basic USB specifications and the situation does not seem to be improving. If all you are after is clean sound, the S3 Pro is a valid choice, but I would like Hidizs to solve some of these basic issues before I recommend any of their products again.
The Hidizs S3 Pro can be purchased here: