Originally Posted by vmachine
...So my question is, in not too scientific terms, what is going on inside these converters that makes them so different?
A lot of things, mostly not the converter itself. The analog circuitry around the converter and the clocking implementation makes a big difference in the sound, even if the converter chips are the same between two different units. Then there is the actual converter itself, which if it has been designed in the last several years with the design intent of being more than bottom of the barrel should work just fine. Specifically what's going on differently depends on the specific device designs.
...Also, is the difference between the two new interfaces and my old RME at least somewhat representative of the differences between lower and higher end converters?...
Not necessarily because "lower end" converters these days work quite well without destroying the sound (of course depending on who you ask you'll hear different answers because everyone's perspective on what "good" is and what is "good enough" for the job differs). What tends to suffer the most in my experience is the quality of components and the way the analog circuitry is implemented around the converter. That stuff is always relatively expensive to do well and requires care to design, quality test and subsequently tweak to perfection. The "lower end" stuff usually employs serviceable, but not by any means exceptional, components and designs that tend to lose some of the extra detail, dimension and "size" you get from high quality analog signal pathways.
...Would the newer RME hdsp 96/32 take care of the latency and "veil over the sound" problems I am having with my older digi 96/8 (and still give me the quality sound reproduction I'm used to)? Would this probably be a better choice than the apparent downgrade from 96/8 to the Roland Quad or Komplete Audio? Is the difference between the Roland Quad and the RME similar to the difference between RME and something like Lynx or Apogee?
You're asking questions that would require all kinds of specific testing to credibly, objectively quantify and qualify. In the end it's hard to say. You just need to go with the best quality design you can afford. It's not guaranteed that any name brand (besides those that are known to always
make the highest quality) will be the answer to your quest, which is why so much of this stuff is so often debated endlessly.
What you can do for practicality sake with any converter is make certain that the analog i/o is as high quality as it can be from mic through the whole rest of the chain. That, combined with the way you use things, will give you much more of what you're probably looking for than you might think and it goes a lot further than any splitting hairs over converters. But if you can
spring for the best conversion it's always a good idea because it makes it that much easier to keep a high quality sound throughout your signal chain when you use excellent components.