If you plan on splashing the cash on a DI box of the highest quality, this versatile red box should definitely be on your audition list!

Founded in Vancouver, Canada, in 2009, Sonic Farm design and manufacture an impressive range of original, high‑quality audio hardware. Uniquely, as far as I can tell, all of their valve‑based products are hybrid designs, featuring EF86 pentode‑based input gain stages and solid‑state outputs. The original version of the company’s 2DI4 Pentode Direct Box was released way back in 2014, and it was already lovely, but now, over a decade on, they’ve decided to expand its feature set. The result is the new 2DI4 MkII reviewed here.

Controls & Features

As with every Sonic Farm product I’ve encountered to date, the workmanship, component quality and construction of the MkII are of the highest quality. The chunky, blood‑red, all‑metal enclosure is similar in outline to that of the original version, but the latter’s solid metal handle has now been replaced by a rubberised strap — a simple but thoughtful change that means it’s now possible to stack multiple units. The inside is different though, with new features and a redesigned circuit board. And it’s not often that I single out a power supply for special praise, but the 2DI4 MkII’s chunky internal toroidal mains transformer and associated filter board were a welcome sight. The fact that this power supply shares an enclosure with unscreened audio circuits, without any detectable impact on its sonic performance, is a testament to Sonic Farm’s engineering skills.

In terms of facilities, the 2DI4 MkII offers the I/O that you’d expect of any DI box, but also a lot more besides. On the left of the front panel is a quarter‑inch jack for the unbalanced 2.2MΩ input, but you’ll also find both an auxiliary input and a headphone output. The aux input can accept the output of a computer, mobile device, media player or Bluetooth receiver, the idea being that it makes it possible to use the device for practice; the aux signal is routed directly to the headphone output, where it can be mixed with the DI signal to taste using the large chicken‑head output level knob (of which more later). The rear panel carries XLR connectors for both that main transformer‑balanced microphone‑level output, as well as an electronically balanced line‑level output. Underneath sit two quarter‑inch jack sockets to carry the buffered instrument‑level thru signal and an unbalanced line‑level output. Note that the aux signal isn’t present on any of these outputs — it’s only auditioned on the dedicated headphone out. Finally, there are a ground‑lift switch, a mains voltage selector and a fused IEC mains connector.

Returning to the front, a blue LED lights to confirm the presence of the EF86’s heater voltage, thus serving as...