Solid State Logic SSL 2 Audio Interface Review (Legacy 4K Mode explained)

Finally an audio interface that can record in 4k. But is it really better than full hd? Hey Julian Kraus here and this is the SSL2 from Solid State Logic. Let's check out its performance, have a listen to the 4k mode and also compare it to other audio interfaces like for example the Scarlett 2i2 and the Moto M2. But before that let's have a look at the hardware side of the SSL2. You can definitely tell that Solid State Logic has its roots in building mixing consoles, because the controls and the design of the interface is very much influenced by the design of professional consoles. The SSL2 has all its connectors on the back side and this leaves the whole top for the controls which makes them very easy to access. On the left you can find the controls for the two input channels. For each channel you got an individual phantom power control, a line button to toggle the input between a mic and line level input and a high z button which when pressed in combination with the line button will change the input to a high z instrument input. Below the buttons you got an led level meter. While i like the inclusion of a level meter i would have liked to see a more granular visualization. With the 10 db increments you can only roughly set your gain and monitor your levels but you're not able to fine tune them. For that you will still have to go into your DAW. For each channel you also got a gain knob and the magic 4k button which we will hear in action a little later in the video. On the top right you got a button which lets you toggle between stereo and mono monitoring and there is also a knob which lets you vary the amount of audio you hear from your DAW and the direct audio from the inputs. Both of these controls are quite nice to have especially because they are not standard on every interface. Below that you find an indicator led which lights up when the interface is connected to a pc and below that you got a knob to control the volume of your connected headphones. Lastly in the middle you can find a very big knob to control the monitor outputs on the back. Speaking of which you got two balanced quarter inch trs outputs on the rear. Right next to them you've got the two xlr and trs combo inputs. The ssl2 features a quarter inch headphone jack and a usb type c connection. I want to highlight that the ssl2 comes with two cables one usb type c and a usb c to usb type a cable. So regardless which of the two connectors your pc uses solid state logic got you covered. Regarding the build quality i would say that the ssl2 is constructed pretty well. Many parts of the housing are made out of metal and all the knobs feel sturdy and turn smoothly. Let's dive a little deeper into the audio quality of the inputs of the ssl2 and start with sample rate. The ssl2 has a maximum sample rate of 192 kilohertz and this enables the interface to have a very flat frequency response even above the human hearing range. My measured response shows a minimal drop-off in the lower frequencies and a near linear response up to about 90 kilohertz. This is exactly what you want to see from an interface like this. Another quality criterion of the audio input is the dynamic range which describes the ratio between the strongest signal the interface can capture and its noise floor. You want this to be as big as possible because with a big dynamic range you can leave yourself a nice amount of headroom while recording and you don't introduce any additional noise. The ssl2 uses a 24-bit analog to digital converter which enables the interface to have a very big dynamic range. The dynamic range for the mic input is stated with 110.5 dba and i measured my particular unit with 110.7 dba. That's a very good value and on par with something like the focusrite 2i2 third generation. Let's talk about the preamps in the ssl2 because solid state logic states the equivalent input noise of the preamps with minus 130.5 dba weighted. The equivalent input noise is a way of stating the noise for a preamp and this can be directly compared to preamps from other devices. I measured the equivalent input noise of my particular unit and it comes in at a staggering minus 130.8 dba weighted. This makes the preamp in the ssl2 ultra low noise and that's why it is currently at the top of my list with the best noise performance i measured so far. If you haven't already noticed you are currently listening to me speaking into a shure sm7b which is plugged directly into the interface. This mic has a very low sensitivity which means that you have to use a lot of gain which brings out the noise. Let me be quiet for a second to let you listen to the noise of this setup. And here is how the preamp noise compares audibly against other interfaces. All recordings have been amplified in post so that you can hear the noise more clearly but other than that there was no additional processing done. And i already know that i will get this question. Do you need a cloud lifter or fathead with the ssl2? No you really don't need to use an additional inline preamp. The preamps in the ssl2 are so low noise that any other external preamp very likely makes the noise performance worse so don't even bother. By the way while testing i noticed that when you turn on or off the phantom power on the ssl2 it shortly mutes both inputs to attenuate any nasty spikes that might occur. That's a nice touch. On the other hand there is no indicator led for the phantom power and from straight above you can't really see if the button is pressed or not. So that's not a nice touch. Now i think it's time to check out the 4k mode on the ssl2. This mode does apparently two things. It produces a slight high frequency boost and also introduces an audible amount of distortion. Solid state logic states that this emulates the sound which their 4000 series eqs are known for. Hence the name 4k. So let's have a listen to a recording first without and then with the 4k mode. As you could hear there is a distinctive difference between the two recordings. One could say that with the 4k mode the audio is more in your face and the sound is brighter and it also has a certain amount of grit added to it. The frequency response shows exactly that. As shown before without the 4k mode the response is very flat and with the 4k mode the whole response is elevated by about two decibels which makes everything slightly louder. Additionally the frequency response rises in the higher frequencies by another two decibels which results in the brighter sound. Like i said the 4k mode also adds distortion. Here you can see the harmonic distortion of the ssl2 with the 4k mode turned off. This results in a total harmonic distortion of 0.0024 percent. When i turn on the 4k mode you can see the dense forest of harmonic overtones and the total harmonic distortion rises to over two percent which is very audible. I know this is a little beyond the scope of this video but i also made some measurements with intermodulation distortion. Here you can see pretty much the same thing with the ccif and smpte measurements where the 4k mode introduces a considerable amount of distortion. So the 4k mode is an artistic feature which you can use to give your sound a bit more bite for the lack of a better word. But be warned if you record something with the 4k mode there is no way to get rid of it afterwards as it is baked into your recording. So use it wisely. Of course i also measured the maximum system gain of the ssl2 because if this is too low you're not able to amplify low sensitive mics sufficiently. The ssl2 comes in at about 55 dbfs at zero dbu which is about five decibels more than your average audio interface which means it has no problems bringing a Shure sm7b up to a proper recording level. And i also checked the input impedance because this shouldn't be too low as it can color your sound. The mic input impedance is 1.2 kilo ohm and even though this is technically enough i would have liked to see a slightly higher impedance of around 3 kilo ohm. So it's a little lower than what i would have expected but it's still okay. One more thing i measured is the round trip latency. This is the time it takes the audio interface to put out a signal and then record it again. So it is a combined input and output latency. You want this to be as short as possible to not perceive any delay when for example using an amp simulator with your electrical guitar. Here are the times i measured with 48k and 192 kilohertz. As always the latency you get heavily depends on the used sample rate and buffer size. So it depends on your current project you're working on. That said compared to other interfaces these are what i would call average latencies. Making high quality audio recordings is one thing but an interface should also be able to put out high quality audio. I'll quickly glance over the line level outputs on the back as they measured very well with a high amount of dynamic range and minimal distortion. The performance of the headphone output deserves a closer look. While the output impedance with around 11 ohm is not terrible it is also not perfect. So there's some room for improvement here. With high impedance headphones the interface performs very well and even delivers a decent amount of power which makes it feasible to even use more difficult to drive headphones like the Sennheiser HD 6xx. With low impedance headphones the performance is sadly not as good. With my 16 ohm and a 32 ohm dummy loads the headphone amp showed an increased amount of distortion which might be audible in some situations. So with the SSL2 use high impedance headphones with 80 ohms and above to get the best sound quality possible. I know i've been teasing you for quite some time now but there will be even more detailed information in an upcoming video where i compare the headphone output quality of many different audio interfaces. So subscribe if you don't want to miss it. Let's wrap up this video. All in all i think the SSL2 is a solid interface. As expected the audio recording capabilities are excellent. The inputs have a very flat frequency response, a nice amount of dynamic range and preamps with incredibly low noise. With high impedance headphones the built-in headphone amp performs pretty well and delivers quite a bit of power. Though with low impedance headphones the performance isn't nearly as good and for the price i would have expected a slightly better performance in this regard. If you're looking for an audio interface with easy to access buttons and knobs i think the SSL2 is definitely worth a look. Okay that's it for now. If this video was useful to you please give me a thumbs up and subscribe if you didn't already do so. I will see you all in the next one!