Upon first look it’s easy to see the Wadia 121’s resemblance to other components in Wadia’s "mini” line, including the 171i i-Pod dock and 151 PowerDAC. Like these other components, the 121 was designed for use in a computer-audio system where it functions as a digital preamp, DAC, and headphone amp. The 121 has multiple digital inputs for AES/EBU, S/PDIF (both coaxial and BNC), TosLink, and USB 2.0. It includes two sets of analog outputs—one set of single-ended RCA and one set of balanced XLR. The 121 also has a ¼" stereo headphone output with its own separate amplifier and power supply on the front panel.
All control functions on the Wadia 121 are operated via its remote. In fact, without the remote there’s little you can do with the 121 since it has no buttons, switches, or knobs on its front (or rear) panel. Only indicator LEDs and the headphone jack populate the faceplate of the 121. With no controls on the front panel, the unit is inoperable if you lose your remote. So, don’t lose your remote.
The Wadia 121 is a completely digital device with no analog inputs. It uses a 32-bit digital volume control, so all attenuation is also done in the digital domain. Every digital volume control will truncate bit-length (and musical data) if it is used at its very lowest settings. To reduce this effect the Wadia’s maximum output level can be adjusted from 4.0V down to 2.0V or even 1.0V, so that at normal listening levels the volume control can be set near its maximum level. On my desktop the 1V setting (using the balanced XLR outputs) was just right.
Since both analog outputs are active simultaneously, hooking up a subwoofer is as easy as connecting a pair of RCA cables between the 121 and the sub. If you require a second, independent line-level output, you can use the front-panel headphone jack. Like many DAC/preamps with headphone jacks on the front panel, when you plug in a headphone the line-level outputs on the back of the unit are muted. But the Wadia goes one better than most DAC/preamps because the 121 stores and remembers the separate volume settings for the headphone and line-level outputs. This prevents the dreaded “Honey, I just blew out my ears when I plugged in my earphones” syndrome.
The Wadia 121 supports up to 192/24 PCM files via its AES/EBU, S/PDIF, and USB inputs. For Mac users the USB input is plug and play, but for PC owners a new driver must be installed to support USB 2.0 capabilities. Whether Windows 8 will support USB 2.0 via built-in drivers is yet to be seen. On a Mac, if you open up the MIDI control panel you will see the Wadia 121 listed as “Wadia USB Audio 2.0.” Under “Clock Source” the control panel reads “Wadia Internal Clock.” This last bit of info corroborates the presence of Wadia’s internal asynchronous USB clocking. Combined with its proprietary “DigiMaster algorithm and filtering technology” Wadia claims “jitter-free playback” from all digital music sources.
In lieu of a detailed technical description of the 121, I asked Wadia’s John Schaffer a series of technical questions about the 121. You’ll find his detailed answers in a separate Q&A box.