We've reviewed quite a few keyboards here at TR, but nothing quite like this one. The Logitech K400 doesn't have mechanical key switches, glow-in-the-dark backlighting, wicked-fast USB 3.0 ports, or powerful macro functionality. It's a basic wireless keyboard with an integrated touchpad. But it's also only $40, and as far as I can tell, it's an excellent fit for home-theater PCs.
Well, the black one is, anyway. Logitech sent us the white version of the K400, whose overwhelming whiteness is a little much for the living room. The pristine aesthetic is especially prone to being stained by Cheeto dust and other snack residue.
I've seen the black version of the K400 in person, and it's a lot more understated despite having a graphic on the touchpad. That variant is well worth the extra $2 over the cheaper white model. Don't just take my word for it, either; Newegg has 327 user reviews of the black version but only four of the white model.
Coloring aside, one of the most striking things about the K400 is how light it is. The keyboard weighs only 0.89 lbs (405 g) according to my kitchen scale. It's easy to pick up with one hand and comfortable to keep propped on one's lap.
The K400's plastic body keeps the weight low, but it's also a little flimsy. The keyboard bends visibly when held from one side, and the entire body can be twisted with only moderate effort. Our sample is curved slightly, as well. The middle of the keyboard bows up, causing visible flex under heavy-handed typing. My last HTPC keyboard was an Enermax Aurora Micro Wireless, whose aluminum body is much stiffer. But I also paid $80 for the thing, and it's about twice the weight of the K400. On the couch, at least, the difference in weight is more noticeable than the difference in rigidity.
At 13.9" (354 mm) wide, the K400 is a few inches narrower than a full-sized desktop keyboard. The integrated touchpad takes up a fair amount of room, resulting in some shrinkage for the key area. Even with a pared-down, laptop-style layout, the alpha key area is 6% narrower and 7% shorter than our full-sized reference. My XL-sized mitts don't feel overly cramped when typing, but my fingers do feel a bit squished together when resting on the WASD triangle.
For brief bouts of typing, the smaller footprint isn't a problem. Neither is the mediocre key feel. However, I couldn't bring myself to write this review on the K400. The key action is too mushy, and the tactile feedback is too vague. I'm not just spoiled by desktop keyboards with mechanical key switches, either. Even Asus' budget-priced Transformer Book T100 convertible tablet has a better key feel.
To Logitech's credit, typing on the K400 generates very little noise. The media keys work as expected, and there's an extra left-click button in the upper left corner. The keyboard is also loaded with function keys tied to Win8 features like search, settings, and application switching. I found the app switching button especially useful, mostly because the associated gesture is unreliable. Which brings us to the touchpad...
The touchpad's surface is recessed about one millimeter into the keyboard. That might not sound like a lot, but it feels like a big drop when executing Win8 gestures that require dragging one's finger onto the touchpad from an outside edge. My finger doesn't always hit the very edge of the tracking surface as it drops down, which seems to impair the recognition of those gestures. App switching is affected, as is access to the Charms bar and application menu.
Otherwise, the keyboard's gesture support is good. The usual assortment of two-finger gestures work right out of the box, with no need to install drivers. The 3.5" tracking are doesn't feel too constrained, but I wish there were a coasting option to extend two-finger scrolling.
I also wish the cursor tracking felt tighter. My fingertip glides across the smooth touchpad surface with ease, but the on-screen cursor lags noticeably. It's almost as if the cursor is sliding on ice. Fortunately, there doesn't seem to be any latency associated with the keyboard response. I didn't notice any obvious signs of input lag while playing Battlefield 4 with the K400 (and a separate mouse).
The K400 interfaces with the host PC via Logitech's Unifying receiver. This dongle plugs into a USB port and is capable of communicating with multiple devices over a 2.4GHz wireless connection. The dongle itself is tiny; in the picture above, it's plugged into the USB port extender that also comes in the box. Below, you can see the dongle tucked into the battery compartment door.
Logitech says the K400 works up to 33' (10 m) away from the receiver, which matches my real-world impressions. The wireless connection even works without line of sight to the receiver.
I haven't spent enough time with the K400 to confirm Logitech's claim that the keyboard's AA batteries are good for two million keystrokes, or about one year of use. However, I can verify that the keyboard's power-saving measures are unobtrusive. Even after being left idle for days, the K400 still responds quickly to both keyboard and touchpad input. Folks who want to conserve power further can turn the keyboard off completely using a switch located on the front edge.
The K400 isn't perfect. Compromises are required to squeeze a keyboard and touchpad into a lightweight, wireless package that retails for $40 or less. But those tradeoffs are reasonable for home-theater PC duty, especially considering the bargain price. Logitech's other wireless keyboard and touchpad combo, the TK820, sells for $100—more than twice the price of the K400.
Anyone shopping for an affordable wireless keyboard and touchpad combo should have the K400 on their short list. This certainly isn't the nicest keyboard around, but the K400 is good enough for occasional use, and it's a solid value overall.