To answer what Steve actually asked in the last question:
Cheap Word Clock cables work out "most of the time", but sometimes there's quality issues with how the cables were assembled, which could result in the cable picking up too much interference and messing with the transmitted clock signal, which can lead to additional jitter, that would not be present with a better cable.
There's ALWAYS some jitter, regardless of the quality of the clock generator. But the goal is to minimize it as much as possible. Better quality cables can help with that.
So, would you likely be able to get the D8B to lock to your audio interfaces word clock signal with that cheap cable - yeah, most likely. But there's a potential that you might get more jitter/interference with the clock signal, which would have a negative impact on the audio quality. If you don't really know what it sounds like if you have a connection with a lot of jitter, you might not even hear it right away. It's not like noticing "oh, there was jitter!". It's more subtle than that.
So, if you just want to get it all set up and working, a cheap word clock cable should do the job. Once you get serious enough about the whole thing, where you notice quality differences between your mixes and others, and can't figure out what you did wrong... that's when I'd start looking into how good your word clock generator (e.g. in the audio interface or in the D8B) is, and if it's necessary to invest in an external Master Clock Generator (e.g. Big Ben... or something like the Lucid unit I'm using... Aardvark used to make one, etc.), and better quality cables.
My recommendation to get started, would be to get that cheap cable and get it all to sync/work together and take it from there.
About the opinions Angelo shared... back in the 90's and early 2000's, Pro Tools was IT for sure, and all the pro studios did use that. Things changed a lot since then, and "pro studios" have been shutting down everywhere, and more and more productions get done at home... sometimes using Pro Tools, sometimes other DAWs. Nowadays, it's a personal preference.
Pro Tools, IMO, is still garbage when it comes to composing electronic music with MIDI. It's possible (Angelo is proof of that), but a PITA, compared to using other DAWs for MIDI based composing.
Pro Tools, however, has some of the fastest workflows for recording bands. So, if my business was to record bands for a living, I'd probably use Pro Tools for that. (You really only take advantage of that, once you have dozens of Pro Tools shortcuts/key commands memorized, and can fly through a session mostly without touching the mouse).
...but I don't record bands for a living. So, I sold the (DSP based) Pro Tools HD system I had many years ago.
In fact, I had two systems. A Pro Tools HD|2 system I got free when I worked for Avid (the 96 I/O converter I had sounded horrible - much worse than more modern budget audio interfaces), and another HD|2 system from when I worked for another well known audio company, that I got free when they threw it out, because it was a PCI-X based system. It only worked with G5 Mac computers (or PC's with PCI-X slots), and that just wasn't doing what other "native CPU" based systems could do by now, when equipped with an Intel i7 processor (or i9 by now).
It's true that latency is an issue - and you're likely to run into this. Your MOTU interface will probably have a round-trip latency of between 8-13 milliseconds. Probably fine if you get it to work at 8 ms... but if you try to record a drummer and do software monitoring at something like 13 milliseconds, it might throw the drummer off a bit.
Because of that, I use the PreSonus Quantum interface, that gives me less than 1 ms latency. Nobody will able to tell the difference between that, and a DSP based system when it comes to latency. So, DSP is not necessarily the answer.
For people who don't mind being stuck on older version of the software, and not being able to use modern plug-ins, etc. (the FabFilter stuff is actually really good, and used by a lot of Pro studios), that's all good. But most people moved on to either newer Pro Tools HDX or "Pro Tools Native" systems, or just moved away from Pro Tools altogether. It's still the "industry standard" for "Professional Studios" that record bands as their main source of income... but such studios are getting less and less. And Pro Tools has long been outdone by other DAWs, when it comes to features that are more important for "at home" songwriters and home-producers. Pro Tools just isn't that practical for that.
...and for what it's worth, I had Grammy-nominated co-workers and was one of the guys authorized to pick up "celebrity" and endorsed artist calls when doing Tech Support... a lot of these well known cats use different DAWs to write music. One pretty famous dude even used Garage Band as his main DAW (...and still called in with questions constantly... sigh...), where he wrote and "prepared" all his songs, before taking them to a "real" studio to get produced properly.
Long story short, I wouldn't get too hung up on any of this, and just make work what you got. You don't have to get the best thing "on paper" right away, to start using your gear and make awesome music. Some of the most productive times in my life were, when I had to sell all my gear (long story) and had only a laptop and a portable audio interface to go along with it. I wrote/recorded more songs with that than I ever did, when I had access to a full studio...
So, while it might have a positive impact on the last bit of extra sound quality, if you get that Master Clock Generator, awesome converters, a DSP based system to avoid latency... and...and...and... I'd just start out with using what you have, and start doing what's most important and what this is all about: Write and record some music.
If you DON'T invest in an external Master Clock Generator, then I'd recommend to use your MOTU interface as the Master, and the D8B as the slave. The MOTU clock is newer, so I'd expect it to be better (lower jitter). But experiment with both, and listen if you hear a difference... and I bet that you will not hear it. It takes quite a bit of experience to notice this sort of thing, so I don't think it's all that important if you're just getting into it more seriously.
Here's an article that is trying to evaluate if you need a Master Clock or not... basically, the conclusion is, that most of the time, in a simple "Digital Pre-Amp/Line-In unit + Audio Interface" setup, it's best to use the clock from the unit you use the inputs on, since this creates the least sync issues/jitter (if I remember it right - didn't read in years):
https://www.soundonsound.com/techniques ... ster-clockSo, per this article, if you were to use the D8B's line-inputs and Pres primarily, you might want to try using the D8B as the clock master, actually. But I'm sceptical when it comes to such an old clock vs. something newer. So, just try, and trust your ears.
A Master Clock starts making a lot of sense, once your setup gets more complex, and you need multiple units run of the same clock. I dodged it for MANY years, and eventually gave in, more for the convenience of things, than for the sound, really.
Having said that, plenty of former co-workers were SWEARING that imaging and jitter improved tremendously, when they added a Master Clock... but that was the same guys who couldn't tell what's a 44.1 kHz vs a 96 kHz recording in a blind test shootout we did at the company back then (I couldn't hear it either, which is why I don't mind working in 44.1 kHz, still - 48 kHz is more common if you do audio for video, btw. Otherwise, I'd stick with 44.1), so I wouldn't take this all that seriously.
Long story short... just get the cheap word clock cable for now. You can worry about all this other stuff once you're knee-deep in producing music for television or when things are taking off in one or the other way for you (Good luck with that... most of us never make it to that point... that's why I'm just in "industry guy" who works behind the curtains).
Even then... a lot of the stuff you hear on the radio nowadays, are home-productions. Heck, even a Madonna album from the late 90's (forgot which) was some dude who produced it all at home... I think with Logic and something like a Echo interface or something. It's really a pretty flat playing field by now. And I've been in this industry since the 90s.
Core message: Just get it working first. Worry about the extra bit of sound quality, etc., later.