That's interesting in that you compared analog and digital synthesizers as I was going to use that as an example. A group called Social Distortion several years back did an entire album using old analog equipment because of the "raw" sound it produced that couldn't be replicated with digital equipment. It gave the album a "warmer" sound as well.
Concerning how do I know if a machine is going to morph or sanitize a signal's audio...There are certain brands of "computerized" detectors that do this. Rather than produce a nice drawn out "raw" audio signal they'll convert what the coil sees into a simple beep ID. From the very quick and unpleasant experience I had using a Whites Prizm I think this machine did this, but I only used one to help somebody set it up and it's been a while so I can't say for sure. I just remember going over a coin with it and instead of hearing a telling long audio response all I heard was a short sanitized beep. My Explorers to me had a little too much of this, though not nearly what other machines have in that respect. I don't like the software converting the audio into a specific ID in such a large fashion that I'm getting a single "word" rather than the entire sentence that the target is trying to say, if you know what I mean. The VDI lag on the Explorer was an obvious problem due to it's processing, but I still don't trust how a machine interprets a target into a VDI response in certain respects.
That's one of the things I like about the Sovereign. The VDI appears to be tied more directly to it's audio. It hears a signal and sounds off to it. The target's conductivity is converted into a voltage level that is output to the meter. These Sovereign meters are nothing more than volt meters. In that way the VDI response is much more "pure" and instant than even machines with much faster recovery speeds. You'll see what I mean after using one for a while compared to say an Explorer.
The big question for me is this- Am I going to feel detached on the Etrac from what the coil is seeing in the ground by either it's audio or VDI processing of that signal? I don't know until I use one for any length of time, but I can tell you that this wasn't something I heard talked about much in the Explorer forums over the years....Yet this "detached" feeling from the detector was very real to me. I didn't like it's shorter audio response and I didn't like the VDI feeling out of phase with it. That's what I'm worried about with the Etrac. Even if it's audio and VDI is "instant", I'm worried I'll find it's processing of that signal leaves me with wanting more information, or at least a signal that hasn't been "corrected" or cleaned up in certain ways.
There are many ways this can happen...Some machines take a slightly scratchy signal and smooth it out for output to the VDI or audio. You sweep over that target with a machine that isn't prone to that and you can hear the slight telling "iffy" audio, or at least see the VDI be somewhat unstable. Another potential problem is with how the machine processes the ground signal. That's one of the things I don't care about automatic ground tracking. It can take a deep target at fringe depth and smooth it out as it tracks the ground so that you'll never hear it, or at the very least the target quickly disappears after you've swept over it a few times to investigate it. I always used fixed ground balance on machines that offered both features. The only time I would ever use track is when the ground was so disturbed that it changed so quickly from "hot to cold" and as a result a static ground balance might miss targets. The same thing can be said for hot rock rejection on some machines. Use that feature and I guarantee you that you are missing some coins at fringe depth or in heavy minerals.
I think in one respect we are missing the trees for the forest when it comes to the Sovereign. It has controls in the style of an "analog" detector but that does not mean it isn't into the digital age in terms of the electronics in the box. Just to run that many frequencies all at once as well as the other aspects that revolve around BBS technology makes it a very "modern" machine in many respects. In fact, despite it's first release years ago the sophistication of the electronics in this detector is well beyond the capabilities of some top of the line detectors made by other companies costing much more in price. Things like BBS eliminating the need for a ground balance, which is very different than a "automatic" or "fixed" balance on other machines that come hardwired that way from the factory. Some have constant ground tracking in them, while others that are "automatic" are really just set at a certain ground balance from the factory. Result is they never achieve the highest performance they could if you could change that setting, and as said automatic tracking has it's problems. BBS doesn't handle the ground signal in the same way as these or just about any other VLF detector on the market. The technology behind that multifrequency is the reason why it doesn't need one, and the reason why they seem to excell in the worst of ground conditions with perfect ID at depth while other machines can't even run stable at such a site.
I'm not knocking the Etrac. I plan to buy one some day. I just hope it lives up to what I expect in a computerized detector. Just like in a sports car I want to "feel" the ground under my wheels (or coil in this instance) to allow me to drive it at top performance. Where that line is drawn is very subjective based on how people expect a machine to respond for them. I won't know for myself until I try one, but if it's even half as bad in that respect as my Explorers were then it's too much software for me.
I'll relate one more anology to the above and then be done with it. Some modern aircraft are "fly by wire" in that they no longer use direct or hydraulic controls in order to control various aspects of the plane's control surfaces. When this style of plane first came out some complained that they lost the "feel" of the plane in the process. On some equipment (not sure if they do it with planes) this loss of feel over the control is compensated for by introducing resistance to the controls. The computer senses what you are trying to do and moves an object based on that. It then senses the amount of resistance that object is producing and then converts that back into a digital signal to send to the control. The control then produces a certain amount of artificial "resistance" in order to mimic what is going on and so that you can feel it.
That kind of setup just makes no sense to me. Not only do you know have many more parts that can go bad, but I feel something is Lost In Translation in the process. As we all know that movie was awful, and so can too much software gumming up the works of a detector.

Bet I'm the first person in the world to ever draw those two parallels together to make a point.

I just hope the Etrac doesn't give me the feeling of "flying by wire" in certain respects. That's all I'm saying...