Molten Music Technology’s KeyStep Mk2 Review: More Brains, Less Brawn?

Arturia’s KeyStep has been the secret handshake of synth nerds and modular heads everywhere. Robin Vincent from Molten Music Technology sets the scene with a mix of nostalgia and dread: the original was nearly perfect, so why mess with it? The Mk2 arrives with a promise of more features, but also a whiff of potential disaster. If you’ve ever plonked a KeyStep down at a gig and just got on with it, you’ll understand the anxiety here.

The new model isn’t just a facelift. It’s a full-on rework, aiming to turn the KeyStep into a songwriting hub rather than just a dead-simple controller. Robin’s torn: there’s more power, but at the cost of that legendary immediacy. The Mk2 is still compact and cute, but now it’s got a screen, menus, and a learning curve. If you’re an old-school KeyStep fan, you might wince—but if you’re after more depth, there’s plenty to dig into.

Arturia’s thrown the kitchen sink at the Mk2’s connectivity. USB-C power, on/off switch, extra modulation outs, sustain pedal—on paper, it’s a connectivity rave. But Robin’s not letting them off the hook: all those rear-facing cables make it a nightmare to butt up against your modular rig. Why not put the ports on the side, like any sensible person would?

There’s also the classic Arturia oversight: no labels on the top for the CV outs, so you’ll be flipping it over or scribbling on it yourself. At least the fiddly micro-switches are gone, replaced by screen-based settings. It’s a win for flexibility, but not quite the ergonomic revolution we were hoping for. If your studio’s a spaghetti junction of cables, prepare for some creative swearing.

Here’s where the old guard might start throwing toasters. The Mk2 ditches those three glorious knobs that made the original and the 37 so immediate. No more glancing down and knowing your tempo, division, or arp mode at a glance. Now it’s buttons, menus, and a screen—welcome to the age of menu-diving.

Robin’s not happy, and neither am I. The loss of instant control hits hardest for live performers and anyone who values muscle memory over menu memory. Sure, you’ll get used to it, but the workflow’s shifted from ‘slam and jam’ to ‘pause and ponder’. If you’re the type who wants to just get on and play, this change might sting.

Let’s not pretend Arturia hasn’t packed the Mk2 with clever sequencing and arpeggiator features. The new pattern modes, mutate functions, and spice controls are a playground for melody-manglers. You can now save up to 64 sequences, chain patterns, and bounce ideas between the arp and sequencer like a sonic ping-pong match. The mutate button alone is a chaos engine—hit it for endless variations, but don’t expect to get back to where you started without some planning.

But here’s the rub: all this power comes at the cost of simplicity. What used to be a one-knob twist is now a button combo and a menu scroll. The creative possibilities are wild, but you’ll need to invest time to master the workflow. If you want to see just how deep the rabbit hole goes, you’ll need to watch Robin’s full video—words can’t do justice to the live jams and happy accidents on display.