ZeroUno SSD is a preamplifier with integrated the ZeroUno PURE DAC, where the output stage is a Solid-State stage designed by CanEVER AUDIO® with the same design philosophy as that of the LaScala PowerAmp, Best Amplifier of 2019 selected by Mono&Stereo.
At the time, when the ZeroUno DAC was introduced, the main design goals of CanEVER AUDIO® regarding that product have been explained in detail. Now the ZeroUno SSD comes with all the building blocks making the ZeroUno DAC a great digital preamp, while adding a high-end analog preamp section with two analog inputs inside the same cabinet.
The ZeroUno SSD can be used as a DAC but can act as the central preamp in a modern high-end audio system to connect all kinds of digital AND analog sources!
The ZeroUno SSD is a high-end pre amp, which can handle all kinds of digital and analog sources.
All analog input signals are operated by a separate circuit implemented in one additional board stacked to the main board of the ZeroUno DAC.
The analog input board comes with a dedicated power supply and works totally independent from the digital circuit of the DAC section.
In addition to the digital inputs of the ZeroUno DAC there are two pairs of single ended RCA connectors for analog sources available on the backside of the ZeroUno SSD.
The digital interface of the ZeroUno SSD is exactly the same as that of the ZeroUno DAC. There are digital inputs for S/PDIF signals via RCA, XLR (AES/EBU), TOSLINK or USB in MQA, PCM and DSD formats. A true 75 Ohms input via a BNC connector is optional as a replacement for the AES/EBU input.
Both analog and digital signals, managed by the ZeroUno SSD, are operated by the same Solid State output stage already introduced for the ZeroUno DAC-HPA.
All input signals are coupled to the volume control by interstage transformers custom made by Lundahl for CanEVER AUDIO®.
The volume control module works 100% in the analog domain for both digital and analog input signals. It is based on a ladder network of pure 0.1% high precision thin film resistors for the lowest possible noise, channel separation and perfect balance between the left and right channel and independently from the volume level. In total there are 127 different positions for volume setting in steps of 0.5dB possible, reaching a dynamic range of 127dB!
In addition to the volume control, there is a level control implemented. This feature let the user adjust the signals from all analog and digital sources to exactly the same level to avoid any increase or decrease in loudness while switching between input channels. The level can be adjusted in steps of 0.5dB in a range of -26 to +17dB.
Each input channel can be activated or muted. So the user can toggle between only those input channels, which are actually connected to a source. Or, if the user wants to compare the sound quality of two different inputs (e.g.: analog records vs digital sources), he can mute all input channels beside those two, which he would like to compare and switch only between them.
To switch between the active input channels the user can push the INPUT button on the front plate or use the MENU button on the RC.
Following the volume control stage is the heart of all ZeroUno products, the Solid State output Stage introduced with the ZeroUno DAC-HPA :
a Solid-State Device (SSD), working in Pure Class A with a super-linear driver, no capacitors or integrated circuits in the signal path and no negative-feedback, with the ability to drive loads below to 600ohms.
This Solid-State Device (SSD) at the output is designed as a small dual mono power amp running in pure Class A mode, which delivers an output power of 2,5Wrms per channel. The ZeroUno SSD can drive any power amplifier, even if with a very low input impedance.
The output impedance is below 1ohm.
In total the signal path inside the ZeroUno SSD is very short and makes use of a minimum number of components for both analog and digital signals.
The final signal of the ZeroUno SSD stage is present via two pairs of single-ended RCA connectors or, optionally, with one pair of balanced XLR connectors (these last are optional).
To balance the output signal a pair of high quality transformers produced by Lundahl due to CanEVER AUDIO® specifications are in use.
Both pairs of output connectors can be used in parallel for bi-amping or to connect an active subwoofer.
Finally, an introduction about the power supplies implemented inside the ZeroUno SSD.
Basically, the power supplies inside the ZeroUno SSD cover about 70% in number of components and board space.
The digital part of the circuit inside the ZeroUno SSD is exactly the same as that of the ZeroUno DAC. It consists of 13 separate ultra-low noise power supplies fed by two toroidal transformers followed by a pre-filtering stage plus 13 discrete analog power supplies designed around four AD797 operational amplifiers.
The analog part of the circuit inside the ZeroUno SSD is based upon six independent power supplies and is designed with the same philosophy in mind as the digital circuit:
four dedicated toroidal transformers followed by four pre-filtering stages, two for the left analog channel, two for the right analog channel.
All analog and digital paths are rigidly separated and powered totally independent to avoid any interference or cross talk.
The toroidal transformers are over dimensioned to avoid any saturation and induction of noise.