In a way, this is not a review of one Weiss device, but two. You see, the Weiss Audio DAC50x platform is made up of two almost identical products; this one, the half-sized DAC501 streaming DAC, and the full sized, but half the height DAC502 streaming DAC. The difference between them is the latter adds a rear-mounted four-pin headphone XLR socket. Everything else, from the interface to the connections right down to the colour of the front panel, is functionally identical. We went for the more conventional audio-sized DAC501 box, complete with a standard 6.3mm stereo headphone jack on the front (which turns out to be a bit of a star).
Daniel Weiss’ concept behind both is to create a new category in audio. “With the DAC50x we are creating a new paradigm for what used to be a black box device”, he says. “A typical D/A Converter is a “set and forget” device. Not so with the DAC50x. It adds a number of interesting signal processing features and sports a variety of digital inputs.” To this end, the DAC501 and 502 both include an extensive range of novel DSP settings.
On the hardware side of both DACs, there are a total of five inputs: AES/EBU or S/PDIF via XLR, Toslink, and RCA sockets, UPnP/DLNA via Ethernet, and USB. There is also a USB A connector used ‘for various applications’ (although these are not described anywhere, I’m suspecting international espionage or juggling are probably not on the list of potential applications). Additionally, both DACs have single-ended line out on a pair of RCA connectors, balanced line-out on a pair of XLR connectors, and a headphone output on a 1/4” stereo headphone jack.
Where most DAC-first audio products consider the headphone amplifier as an afterthought, the Weiss uses discrete output stages for both line and headphone outputs. The output levels of both can be set to adapt for the headphones or amplifier in the chain, using a coarse four-step adjustment. These levels can be set independently for line- and headphone outputs, and there are no sound-degrading servo mechanisms used anywhere in the Weiss DAC50x models.
Common to Weiss Engineering models of past and present, Daniel Weiss is reluctant to discuss the make and model of the DAC chips used inside his devices, and the DAC501 is no exception, preferring instead to describe the digital conversion as using two 32 bit D/A Converter chips, with two D/A conversion channels used for each audio channel. This chipset is governed by an internal high precision, low jitter clock generator. Uniquely, the sampling frequency of that generator is fixed at 195kHz, not 192kHz or 176kHz. The input signals are converted to the 195kHz sampling frequency because Weiss claims this gives optimal signal quality, reducing any jitter related effects in the process. All standard PCM sampling frequencies from 44.1kHz up to 384kHz plus DSD x64 and x128 are supported.
Weiss opted for a linear power supply in the DAC501, with separate regulators for left and right channels and two separate toroidal mains transformers and automatic selection of mains voltage from country to country, measuring the voltage before power up, so your fine DAC is not blown apart by mistake. Even the power switch is different from most, as it activates a semiconductor relay which only switches on or off at the zero crossing of the mains voltage. This means glitch free power switching.