Focusrite tell us that the Scarlett 2i2 USB audio interface is the world's best selling audio interface. We have no way of verifying this but we sure see a lot of them, We have one here and it comes in jolly useful and sounds good too.
The new 3rd Generation Scarlett range now adds higher specced pre-amps, plus the AIR circuitry found on the Clarett and ISA products (more expensive) plus the new range now all have USB-C connections.
We took a look at the 18i20 - the top of the range and featuring 18 inputs and 20 outputs.
8 mic preamps all with pad and AIR, on combi connectors (XLR/jack) with the first two on the front panel also switchable between to instrument inputs.
10 analog balanced outputs, with monitors pre configured to 1+2 plus an alt speaker routing to 3+4 should you wish.
Note, the Scarletts are not DC Coupled so you wont be able to directly hook up modular gear, but we used the Expert Sleepers ES-3 and the ADAT output. The 18i20 allows for SMUX connections, up to 96kHz over adat so you have 2 sets of ADAT ports, plus an S-PDIF on RCA (in and out)
USB-C the Scarlett comes with an A (flat USB connector) to USB-C so you can hook this up to prety much any USB-2 equipped computer - as long as the OS is supported. Focusrite tell us they generally this is officially "current - 1" so on Mac thats 10.14 and 10.13, though I'm using 10.12 and with the latest firmware and Focusrite Control editor (previously there were some clocking issues at 44.1, which appear to have been fixed), it was fine. On Windows expect 8.1 up. The 18i20 requires additional power and has a 3 pin IEC socket on the back, you can also fix the included rack ears for 19 mounting.
We tested with synths, effects and mics and the quality of the synth signal was indeed fulsome - plenty of low end and fizz. We also took the tambourine test - with difficult transients, this can max out lesser A/D convertors, but it was again fine. Noise levels were pretty much non-existent on the ribbon mic we tested using all of the 56dB of gain the mic pres can give.
Front Panel Control
All analog input channels have a gain control and metering, with a dedicated pad switch, engaging the AIR function (a +4dB curve from 100Hz to 4kHz) is in software only on this model but has a display on the front panel per channel.
AIR adds a sort of tilt EQ/curve and can greatly benefit dull or neutral sound sources (sounded great on the ribbon), its taken from their much more expensive ISA range and is applied in circuitry on the way in (so would be recorded).
I would have liked to have seen a 75 or 80Hz high pass filter, but there isn't one.
Monitor control has volume, dim, mute and alt - you can switch between sets of speakers via this switch if you configure it in software, similarly you can set the volume to affect any pair of analog outs, or all - handy for surround.
Unfortunately its not possible to preset the Dim level and I found it to be a little low.
Two sets of headphone outputs mirror outputs 7/8 and 9/10 and have dedicated level and a reasonably loud output.
The routing options are legion yet pretty simple to setup - each set of outputs, analog/ADAT/RCA all get a mix source and can be from inputs to DAW playback. So its pretty easy to set up complex mixes between the computer and live inputs with an adjustable level, mute, solo control. Mixes can be saved to the local computer. its here that I'm puzzled why there isn't direct MIDI control of some of this stuff, as it would be a useful addition (either USB Midi or via the In/Out ports on the back)., However this isn't just Focusrite that don't do this. So maybe irt will be a new thing one day.
So I should reiterate that you don't need a USB-C equipped computer for this to work - the cable from A to C comes included. I chose to go direct, as we had a couple of USB-C cables here and the Macbook we used also has it. However it seems not all USB-C cables are created equal - the first one I used definitely did not supply a stable connection and I had all sorts of clocking issues - so make sure you have a high quality cable if going direct.
There's probably a Scarlett to suit your needs in the range form the Solo right up to the 18i20 there's 8 of them. All equipped with AIR as well. I found I could run this at 64 or even 32 samples for some really low latency operation, processing live inputs etc, but obviously this will ultimately depend on your CPU, We used a late 2016 Macbook Pro i7 2.4gHz with 16GB of RAM so certainly nothing too special. We also did not have the chance to test the issues some people are experiencing with more current Apple computers and the T2 security chip that can interrupt the USB data flow and therefore make for glitchy audio. (read more about that here)
Certainly the Scarlett 3rd Gen range continues to offer a high quality audio solution at a reasonable price.
Solo - £99.99, Solo Studio - £199.99, 2i2 - £149.99, 2i2 Studio - £249.99, 4i4 - £199.99, 8i6 - £249.99, 18i8 - £349.99
18i20 - £449.99