Setup and User Experience: Part 1

The iFi Pro iDSD Signature offers a rich variety of inputs and outputs so you can decide how exactly to use it. The bare minimum required on the input side is the power cable itself and relying on the integrated WiFi antenna for use as a network streamer. Seen above is the unit with the provided iFi RCA interconnects and the external WiFi antenna plugged in along with the USB cable for using the USB input from my PC. In practice I found myself using the Pro iDSD Signature as an all-in-one device to drive headphones and IEMs in addition to purely as a DAC and streamer with the balanced XLR outputs leading to my e-stat amplifiers. Seen above is also the iPower Elite external power supply next to the Pro iDSD Signature to give you a better idea of how it stacks up size wise and how easy it can be to hide it from sight. I do wish the cable was less conspicuous though. Once connected, you can press the power button on the front to turn on the unit which will in turn will also light up the OLED display as seen above.


The OLED display is extremely useful to have here once past the initial branding it displays during the start up sequence. It defaults to showing the current playback type and rate, the filter used, as well as the input method itself. This means you can easily use the various input selectors and filters to go through the options available and rely on the display to ensure you are on the right step. It is bright enough to be usable in a well-lit environment and is large combined with having a decent enough resolution to not trouble your eyes much either. I do recommend turning down the brightness as much as you are comfortable with to avoid any OLED burn-in issues over the long run. There's also the iFi logo on the front which has RGB LEDs behind it that turn green when the device is warming up, white in solid state mode, orange in either tube mode, and red when in a protection mode to complement the information provided on the OLED display.


The iFi Pro iDSD Signature supports a pure solid state output that relies on J-FET based circuit of fully-discrete Class A topology. There are also two GE NOS 5670 tubes inside, as previously seen, allowing for Tube and Tube+ modes. The former simply switches the J-FET circuitry to tube-based Class A analog section (Class AB with low impedance headphones/IEMs) whereas Tube+ reduces available negative feedback as much as possible to where you get more of the tube's natural harmonic distortion for a more pronounced tube-y sound, keeping in mind that even order harmonics dominate. The tube heater element turns on with the unit to keep it ready for either tube modes although it does shut off and turn off the tubes after a certain amount of time in solid state mode. This means you will have to turn the output mode switch to either tube mode and wait for the heater element to warm up the tubes enough before these modes are active—audio will play in the solid state mode until then even if the switch is in tube mode. This takes a couple of minutes at most and helps prevent wear on the tubes in addition to having a system that you can easily toggle between the three modes for testing. I do recommend finding the output mode you prefer with the headphones you are using and then sticking with it as much as possible though. Seen above are also FLIR thermal images showing the iFi Pro iDSD Signature never gets absurdly hot to the touch and you can easily hold it by the sides for re-positioning too. It's best to not touch it once you have it in the desired location and allow for some breathing room all around the unit too. The iPower Elite gets an LED that turns on when it has power and we see the integrated heatsinks work well there too.


The iFi Pro iDSD Signature isn't a completely new product and this particular unit may well have been making the rounds with other reviewers so I wanted to first make sure there was no pending firmware update before I did any serious testing. Head over to this page where you will need to select the product from the drop-down menu and then enter the serial number of the unit—found on the sticker on the back with the QR code that leads you to this very page—to gain access to the various software drivers and any applicable firmware too. There was one such update from September 2021 available and I do wish iFi had a more detailed update log than just "Bug Fixes," but seen above is the update process which takes no more than two minutes and gets the Pro iDSD Signature ready.


Using the Pro iDSD Signature with Windows 10 or 11 doesn't require any additional drivers, with Windows recognizing the device automatically. We see that the default firmware provides PCM playback options up to 32-bit, 384 kHz. The integrated USB encoder bridge comes in handy here, and all your favorite players will recognize the device in WASAPI (Windows Audio Session API) mode accordingly. There should be equivalent drivers pre-configured in newer macOS builds too, but I am not familiar enough to speak on this front.


If you have a device that doesn't accept UAC 2.0, or even if you simply want to try other options, then the iFi USB audio device drivers will be of interest to you. You can find the installer on the same page as mentioned before and the latest version at the time of testing was v5.12.0. Installation is trivial as seen above, and these drivers now allow you to make the most of the iFi Pro iDSD Signature within the Windows OS as well as with other products connected to the device as either input or output.



What it then does is create a new output device in Windows, also providing access to the iFi USB Audio Device Control Panel. Just be sure to set the format to 32-bit (or whatever else is preferred) and choose the ASIO (Audio Stream Input/Output) buffer size that suits your latency requirements—that's about it. With that done, go to your media player of choice. I demonstrated above with JRiver again and set the audio player to the same output. At this point, you can implement further tweaks, but those are player dependent.