I have to say two things... do you know what you want to do with an interface? And... don't stress this to much. In the price range of the Scarlett stuff, most things in that market are really decent in comparison. I.e. none of them will allow you to turn their internal preamps off to use, say a Neve or Avalon or etc. etc. etc. preamp. Even the UA Apollo Duo doesn't have such a feature, and the rack units have it to where the first 4 channels are internal preamp, and the last 4 have no preamp.
The 2000 dollar rack UA and the Audient are really the first points of entry to having any sort of option to turn off or not have internal preamps. These are also where converter quality starts taking a real jump up, which you'll most notice when pushing things... especially on the DA to AD side.
Depending on how good you are as a mixer, you can really make things lively and the Scarlett price range really shines in helping people really get some tracks recorded that are clean conversion wise, and the preamps in many of those units are given the flat treatment so none of them tend to color sound too much. The advantage here is that you can always color things later with analog modeling plugins of all sorts.
Some of that is pretty obvious, but if recording is your aim, I think it helps break down key issues versus unit versus unit. When it comes to Focusrite and Stienberg and Presonus... they're all killer units for the price. I got a Scarlett 2 channel interface because I have a friend who has the 4 channel one, and I thought it might make any collaborative efforts easier if we want to expand inputs. Sometimes the choice is that simple. LOL I ended up getting a POD XG too(think that's the letters) so I could track with plugin models without latency when I'm in writing demo mode. I've found that it's similarly comparable to the Scarlett in terms of conversion and preamp levels. The question of whether you need to jump up to the much more expensive route of Apollo Quad, Audient, Apogee's range, or Antelope really gets into how many tracks you need to record at the same time, whether you need to mix in and out of the box (good enough DA to AD to be able to push the 2 bus and enough outs to send to multiple hardware units), etc. The price can really not be worth it for what some people's ears will even be able to hear. Unless you start doing certain things with it, you might not notice that an expensive converter is all that much different unless you're comparing it to a really bad one. In something like the AX8, the conversion is so important because so much saturation of sound is happening in creating these models. Most digital sizzle that modeling tends to have comes from an inablility to really convert all that complex high end. This is a place you'll notice converter quality in interfaces the same way... usually you'll catch it during mixing. You'll suddenly notice that even though your guitars aren't anywhere near clipping even in average level, yet there is digital overload sounding distortion and turning down the volume seems to help. Usually you first notice it if you're doing editing with headphones through the laptop's headphone jack. When it goes away after you get the interface hooked up... your DA to AD conversion in that box has just been revealed to be far superior to your laptop's. If both do it... it might have even recorded that way and some serious low pass filtering is gonna be necessary. Just an example... it can be more complicated than that for sure, but its an idea of the sorts of things that pop up. You might still run into those sorts of things with any of the lower priced models... yet, they're still good enough that its usually not hard to work around.
If you're just talking about live situations, you need a quality direct box, not an interface.
If you're talking about live situations and you aren't in a band with a PA and have yet to buy one for your solo shows, or are responsible for buying it for your band, then that's a whole other ball of wax, and I'll definitely say that the Behringer stuff is priced at a point that you can't go wrong to get it and start making some money with. Especially with the Midas influence.
But again... really the whole point of such a long detailed post is to just say that whatever you do, you can't really go wrong as long as what you need to do is supported by whatever you get. Don't get a one channel interface if you want to record your guitar and your vocal in one pass. lol Whatever you want to do, the sound quality of things today is really quite amazing and you really can do wonderous things at home, so even if you realize you need to upgrade in the future, don't worry that you'll make bad sounding stuff in the meantime because as long as you watch your levels and listen for crackles, you'll be fine.
