I used one of those for years teamed up with an 8 track. First a Tascam cassette then latter the Yamaha MD8 digital. I always used the direct outs as it was a no brainier. I still have the short wiring harness ( 1/4" to RCA x 8 ) It had the pod thing on the bottom to add more XLR channels right? 
And it was cool ( If I remember ) that the direct outs were separate from the insert jacks? Right? Cause I think I had 3 channels with compressors patched in too. 
I used all the aux for cue mixes and effects. 
I was a fool for selling it but I needed the cash to buy my 01V.  
But one thing I do sort of remember was that Mackie reversed pin 2 and 3 on the main outputs so your out of phase with some gear..could be ? long time ago and I have a very small brain... need more banana coffee...
 
Your gunna love using a mixer, I couldn't be without one

As I was doing my morning wake up routine I was checking out a bunch of youtube vids showcasing various CR1604 models (many of which I watched a few years back but didn't fully understand) so I'm now seeing some of the main differences between the original (which is the one I have), the VLZ (which is the one that came out after that corrected some design complaints and is the one I think Leadfoot has) and some of the newer models.
 
The original (the one I'm using) is the one that only has the 6 XLR inputs built in and the rest are line in only. That was something that people didn't like for obvious reasons so they released the additional pod to allow XLR input on the last ten channels (which I have). So yeah... if you had the extension pod it was likely the original. The next model they built the extra XLR ins right into the unit. They also moved a bunch of crap around and added some stuff like tape in I think and separated the direct outs from the inserts.
 
Basically the direct outs (which are labeled Channel Access) on mine are a combo jack that act as inserts as well as direct outs depending on the cable and how far you have it pushed in. A T/S cable pushed halfway in is the direct out that still allows that channel to be heard through the Master output, a T/S pushed all the way in is a direct output that "interrupts" the signal going to the master (which I'm guessing means it can't be heard through the headphones, mains, etc) and a TRS cable pushed all the way in is a proper in/out insert for effects. It's a little confusing. They have their own little block of connections on the back of the unit as opposed to the models after that have the inserts right on each channel (along with the XLR/line in connections) and a separate block of connections specifically for direct outputs.
 
The other thing they improved after this model was the input trim. On mine they are above the channel input connections (which is kind of a pain to get at and they are those tiny little knobs instead of a full sized knob like  all the other controls). In HOWEVER they also kind of made things a little stupider and unnecessarily complex in many ways so as much as I'd like to have a tape in and trim knobs at the top of the strip and whatever they messed with the buss/aux routing making it more limiting/confusing, tied the headphone output to the Master (which are controlled independently on mine via a fader which is nice) and the really new ones do not look nearly as sturdy.
 
Unfortunately my model is before the introduction of the Onyx preamps which are supposedly really nice (and you would probably have them Leadfoot) but I'm finding that I'm getting some very nice sound with what I have. Perhaps it is even better suited to what I do anyway.
 
The one thing is I also looked around at what these boards are going for and it seems they can be had for pretty cheap. Like around $250 BUT they all seem to be beat to hell and/or don't have the pod. I saw a couple guys trying to sell their for $500 (and one guy was even trying for $800 but he ain't gonna get it) so IDK. I think there is far more functional value to the thing than monetary and honestly I'm done selling gear. I got rid of all my crap/unneeded stuff already and kept this thing for a reason and now it is definitely serving its purpose.
 
I spent a couple hours trying out some sounds through my Keeley MT-2 into the Line 6 into the board (with a light spicing up with the EQ which is AWESOME) and then into Sonar and I'm getting a pretty darn searing, gutsy chunk out of it all.
 
Now if I could just remember how the heck the guitar parts of my current project go I'll be in business. lol

I've just re-integrated a little Mackie mixer to my set up. At first I figured that the USB port would provide an easy solution for 2 way connectivity, but since it's USB 1.1 and 16-bit only, I had to resort to traditional cables.
 
In this case, because there is no Alt Out, this meant using Aux sends to send the signal to my Scarlett. Does it degrade the signal? I don't know. All I can say is that being able to use the Mackie's EQ on the way in outweigh any disadvantage - especially if I'm tracking with the POD HD. 
 
 

I often use a VLZ Mackie. I use the 3/4 Alt bus (which pressing the channel mutes directs the signal to) to record from. Using the mono channel inserts doesn't work for me because I use the stereo channels for synths and they have no insert points. Also I have a compressor occupying channel 1and 2 inserts.

The mixer mains feed a pair of monitors.

Aux 1and 2 are used for delays. These are set fully wet and are used for monitoring only, not sent to the 3/4 bus and so not recorded.

If I needed to use that mixer to record e.g. a drum kit then I would use the mono inserts to split the kit up into tracks in Sonar. I only need (usually) to record one synth at a time, so a stereo pair of outputs works fine for that.

As for noise, can't say I've noticed much unless I crank a channel preamp too much. Crosstalk generally not a problem either. I usually leave the eq flat other than applying the lo-cut rolloff to channels without much bass in them.

So after working on this most of the afternoon (well the past three days really) I've got things working quite well for my first configuration (Guit to TU-2 with one split going to the Metal Zone into the Line 6 set to split channel and then two outputs going to the board and the second split from the TU-2 going to the multi in on the interface). As much as I wanted to try out the Aux outs (mostly because I finally learned how to use them really) and having that extra level control I've read up on all devices involved and general gain staging with hardware and it's now kind of a no brainer set it and forget it situation with the direct outs (and in retrospect the extra level knob would probably be just one more thing to think about). I'm getting a LOT of sweet bite and crunch out of the board so this seems to be a success. The only crummy thing is the hum from the MT-2 but the sims do that anyway. It was a lot of work too because I had to deal with troubleshooting wonked cables and making decisions on what devices should have which levels set how (the sound wasn't quite as good if I sent the signal into the board hotter with the trim turned down so I turned the output on the Line6 down despite the L6 manual stating that it should be turned up more than anything else but whatever... I guess the board preamps like being pushed a little). All in all a successful and functional experiment. This tone will go onto my current recording.
 
I do think I may get better results from the Traynor. I also want to toss some mics into things but that is going to be a much more elaborate experiment and I'll have to clean up the tiny room a bit to accommodate stands and whatnot.
 
I also discovered ANOTHER tuner pedal I have that might act as a splitter so I'm trying to wrap my brain around maybe having both amps running while still having a direct in going to the interface. Currently it's an either or type deal. Eventually once I learn more about what works best for what I won't need these elaborate set ups (I can just make a plan for the track and hook things up the way they need to be) but for now the luxury of all these different sources should be useful.
 
I really do need a proper DI splitter thingie though but I have more important purchases to make at the moment.
 

Rain
I've just re-integrated a little Mackie mixer to my set up. At first I figured that the USB port would provide an easy solution for 2 way connectivity, but since it's USB 1.1 and 16-bit only, I had to resort to traditional cables.
 
In this case, because there is no Alt Out, this meant using Aux sends to send the signal to my Scarlett. Does it degrade the signal? I don't know. All I can say is that being able to use the Mackie's EQ on the way in outweigh any disadvantage - especially if I'm tracking with the POD HD. 
 

After messing around with this all afternoon I gotta say the best part of running through this Mackie is definitely the EQ. I barely have to touch the thing to drastically alter the sound and it pretty much ALWAYS seems to alter it in a good way as opposed to other boards I've owned where I seem to be chasing the sound I want but never quite catching it.
 
Very nice.

tlw
 I usually leave the eq flat other than applying the lo-cut rolloff to channels without much bass in them.

I wish this model had that low cut as well as the Frequency knob for the mid that the later versions have but really the basic three band is pretty impressive.

The low cut at 100Hz is one of the reasons I picked the Mackie instead of the other mixers I was considering. In conjunction with the low shelf at 80Hz, it allows me to really clean up the POD HD.
 
A little notch at 2.5 takes care of the rest and the guitar just seems to sit in the mix so much better, right from the start. I got so carried away with it that I spent almost 2 hours jamming with that set up last night, just for fun. It really tightens things up.
 
 

When you get it set the way you like it, let us hear how it sounds!

I have a CR1604-VLZ that I bought new in 1997.  In my current setup I use the direct outs either directly into my Delta 1010 or into a rack of dbx 160A compressors (which then go into the Delta 1010).  This setup works great for recording drums
 
The board is designed for split monitoring, or in other words, record to tape using channels 1-8 and then monitor back through the board using channels 9-16.
 
“Traditionally” there were two methods to output to tape using the Mackie.  Either the DIRECT OUTS or the SUB OUTS.  At that point in the history of home multitrack recording, if you wanted to maximize your routing flexibility you would use the DIRECT OUTS of channels 1-4 into channels 1-4 of your multitrack recorder and then use the 4 SUB OUTS into channels 5-8 of the multitrack recorder.  It was (is?) also possible to use splitter cables on the 4 SUB OUTS into all 8 inputs on the multitrack.
 
Because you are monitoring through your DAW and not back through the board you can essentially just throw “traditional” out the window and route anyway that works for your needs.
 

 
 

@Leadfoot... I was actually thinking of creating a project to specifically to try out and document all the various input configurations I have at my disposal so I could reference it when I'm writing/recording. That way instead of trying to just "remember" what things sounded like I can actually open the bugger up and comb through the various set ups. However there are a LOT of variables and I want to test them all. I've started plotting them all out in a notepad document so I have diagrams to follow when I get around to implementing them.
After a day of making some maps I realized... well this is a BIG undertaking because there are so many variables. I have 2 amps (well one and a half... the Line 6 head and the Traynor which I use as a cab for the Line 6 as needed) with LOTS of possible output combinations (as well as two smaller practice amps with basic line outs and obviously speakers that can be mic'd). The Line 6 itself has 2 channels each with 8 distinct models (for a total of 16) which all have their uses. I have 3 guitars and a bass that need to be tested as well as my acoustic. I have about two dozen mics that are all kind of "so so" but some are really interesting and many are just workhorses that with some coaxing and skillful placement should get some interesting textures going. I have two interfaces with their own unique mic pres (Layla 3g and the Scarlett but I'll probably just stick to the Scarlett). I have two mixers (the Mackie in question and a cheapo Alto that probably isn't worth even hooking up). I have various stomp boxes (like a Dunlop Gain, Boss Yellow(s), the Keeley MT-2, a Death Metal pedal, some weird Korg multi effect pedal with a rocker pedal on it that has some crazy banks and is programmable and I probably have some other boxes I'm forgetting). I've also got TH2 (full version) and GR5 which obviously add about a million other possibilities but that's post input.
 
Obviously then there is mic positioning and EQ and all sorts of other physical factors.
 
Sooo... yeah. It started getting a little overwhelming BUT I figure I can experiment and catalog all this stuff over time and keep a master document on how I did it all. Honestly my gear is mostly crap or at the very least not "ideal" so these types of experiments will help me figure out what works and for what and what doesn't as well as be good practice for setting things up and making critical decisions.
 
For now I'm starting with the simplest, most logical set up for this current project and if I get a chance I'll do a quick export of the tones I'm getting. I am however hoping to get this project done sooner rather than later and post it so either way it's gonna be available.
 
Yes... I'm a little crazy. ;-p
 
@QuantumEffect... I've used the Mackie on drums and it is very nice BUT I kept screwing it up. I would always get this nasty "pinging" sound and I think I now know why. I believe that was some kind of loopback thing happening because I only had the direct out Channel Access pushed halfway in so the signal was heading to the master as well instead of just going direct out (must be pushed ALL the way into the Channel Access). I tried the split monitoring thing too for mixing and mixdown but it never worked for the same reason. Just destroyed the signal. However I cannot be sure if that is what was going on because... well I was very drunk back then and was extremely lacking in knowledge. I'm feeling much better now. lol
 
Also I should probably set my input pod up like you have in that pic. My "studio" is tiny and reaching around the back of the mixer to plug things in/out and just look at what's what back their is really hard on my back (which is a total mess). Not sure why I never bothered doing that before but it was probably fear of breaking the thing due to numbskullery. I'm sure it is much simpler than I've psyched myself out to believe.
 
Cheers, guys.