Ever since I heard of Aphex and their "Aural Exciter" I've been intrigued by such units but also somewhat questioned their use - can't we just adjust things in the mix, cutting and boosting tracks to achieve clarity and separation? I still, even now, feel that these processors are a bit of a "trick", to be added to a track to rescue it and make it better than it might otherwise be through hard work alone. And that's the point! There comes a moment in the track's creation where some broader processing is worth trying, and it doesn't always need to sound obvious, sometimes a very slight lift in the track *as a whole* makes a lot of difference, and that's how I have started to use this unit.
It's easy to overdo anything with outboard units, you get used to a certain amount of excess and then to recapture the magic you have to take it further next time, and with this you need to be quite cautious so as not to lose the result you're after.
Using this on a track has made me think a bit harder about what it is I'm going for every time, because it works subtly and differently according to the balance and instrumentation in the track. Acoustic guitars are in most things I make and this is very good at breathing life into the acoustic elements of the music and making their presence felt, and that's my main use for it. It also works quite well at highlighting my bass parts, especially on 5-string, but there are no settings I can actually recommend with it because every mix has to be approached differently.
I had to use the controls quite coarsely to begin with, just to feel what the processor was doing, and I find often that I need to start this way and then back off on the settings until I don't feel they're having any effect anymore. Then A-B the mix and listen for the changes. It can reach the point where the track sounds almost the same with or without the SX3040 in the signal path but there's some subliminal improvement with it in. I think that for me this is how I like to use it.
The controls seem fairly substantial, however they are not attached to the front panel but the circuit boards inside (so I learned), which is fine if the unit sits in a studio rack as mine does. It is a potential point of weakness if this unit ever travels around, though. I'd feel happier with them attached to the front panel and then to the circuits behind.
I'm used to guitar effects and hardware synths that all create obvious results when you twist a control somewhere, so it's a bit strange to have a unit that to do its job properly means setting it so that you barely notice what it is doing - that can be frustrating sometimes! I also tend to mix roughly and leave tracks alone after that, and this is compelling me to pay more attention to the final results, which again is frustrating when I want to move on to something else, but which actually makes a difference to the final result.
Is it "as good as an Aural Exciter"? I really can't say. A top producer would have to express that opinion because they are more likely to see these units from a professional perspective and regular use. In studios, does the amazing result stem from the hardware alone, or the producer's touch? All I'm qualified to say is that the unit does have an effect, and that it is best when it is subtly used, if you want a natural sound as I do, and that effect always lifts a track in ways that sometimes it is hard toi describe. Instruments sound a bit more transparent and separated, and done properly a mix can gain some definition you thought you'd lost along the way. I'm a happy user.