Responding to Roscoeiii - using the 4 DEQX presets as part of the setup process, this has been my experience over the past 2 1/2 years:
1. With DEQX processing switched out of the system, I thought music sounded OK but imaging was rather flat and 2 dimensional. The subs were blended pretty well but occasionally a particular low frequency jumped out or there was some boxiness or a dip. The speakers didn't cope so well with the different frequency wavelengths and room reflections, as well as imperfect time alignment between the drivers themselves
2. With just DEQX speaker correction (I use active crossovers sub-mid-treble) the system sounds very different, images become much more pin-point and the soundstage sounds more natural. Music starts to sound 'realistic'
3. With time correction added (set manually after measuring) it is like turning the focus on a lens and at the right setting the difference is quite stunning, even from the last stage above. Images sit in a believable 3D soundstage (if on the original recording). The acoustics of the recording venue become very apparent for the first time. Vocals sound like the performer in front of the listening seat and even in a complex passage you can hear all the instruments individually and clearly. This is not like being at a live venue however (which I do A LOT), I guess it must be more like being in the original recording studio
4. Room equalisation becomes almost unnecessary even though at stage 1 there were dropouts and humps, especially in the bass. At most I have only needed +/- 2db in a few of the lower frequencies. Switching room eq in/out actually makes relatively little difference. With this in place, I have a system that betters anything else I have heard in over 40 years of trying. Not to say that there isn't something better of course
I use 3 of the 4 preset settings to subtly alter bass response to accommodate different recordings (some albums are bass light, others heavy) - listening most of the time to setting 2 of 4 which is 'flat'. The final preset (same settings as preset 1) uses very steep crossover slopes which give faster dynamics and transient attack on an appropriate recording or when I feel like it!
Time delays have a very marked impact on a speakers' output and in fact you can tailor the sound quite dramatically using this alone. Delaying mid-treble to sub-bass slightly longer than 'correct' will create a quite pleasant 'growl' to bass guitars if that is what you want. Likewise it is worth tweaking the sound slightly beyond 'flat' to give exactly what you prefer...always retaining a smooth response, unaffected by the room in any way. That is a real benefit of DEQX - you only hear the recording via natural sounding speakers, not the room you are in. If you use low order crossover slopes, music is generally more laid back whereas with the steepest slopes, transients can become quite spectacular. Yes, a more forward or laid back sound can easily be produced from any given set of speakers, in fact I have discovered that you can tailor to EXACTLY what you want. For me, DEQX combined with Open Baffle speakers and subs does that
Answering the final point about different brands of speakers, I tried that too back in 2012 (B&W, Shahinian, Royd, Castle, some floorstanders, some not) and in 3 different rooms. All end up sounding remarkably similar which makes sense I suppose because you start the process measuring (outdoors in my case) and calibrating 'flat' and then again in the room. DEQX creates a set of filters that replicate the same 'flat' response, adjusting driver phase and timing accordingly for each type so the end result is much closer than you would expect
I implied it previously in this thread but I will repeat it again - DEQX repays the effort you put into understanding it fully as long as you take advantage of everything it has to offer. This is as near to ideal as I could possibly hope for and in the past few years I tend to just listen to the music itself. Isn't that the whole point of this?