Not exactly clear what you are trying to do. I assume that right now you are using the digi preamps in channels 1-4 and have the 3124 plugged into the line inputs for channels 5-8.

If you want to use channels 9-16 you will have to buy a preamp and an AD converter and hook the converter to the 002 via ADAT. The octopre or octopre LE with the optional ADAT card would be an option for this. This completely bypasses the 002s preamps and converters.

If you are simply looking to plug a preamp like the 3124 into the line inputs in channels 1-4 that's another story. Frankly I don't really know which parts of the digi preamps are bypassed by the line inputs. But you have something better than a block diagram. You can just plug your 3124 into channels 1-4 and see what you think of the sound.

On the octopre - the non-LE has a compressor/limiter on each channel. I have one. The compressor/limiters are nothing to write home about. The preamps are a little better than the digi, but closer to the digi than the 3124. But if you need 8 channels of AD conversion - it gives you that for $1K with all of the other stuff thrown in. Basically a lot of feature that are just OK for a good price.

Thank you! That is what I want to do, use channel 9-16 Any sugestion about ad converters price-quality and pre amp 8 channels.

like M-Audio Octane 8 ch. preamp AD converter ADAT lightpipe

I think you have a big problem here? You have incredible great sounding API 3124 microphone preamps. Anything else will sound funky in comparison. Funky not being a good adjective. Adjective? Having flunked English my audio sounds better. Particularly since I own a couple of those 3124's. Don't get me wrong. There are lots of better sounding preamps but better doesn't necessarily mean better. If you like the way your drums sound, vocals sound, instruments sound with the 3124? You'll be even more confused when you hear "better" preamps that really aren't. So I might suggest is that you try to find something similar to the 3124. What could be similar & affordable? Most anything with a Dean Jensen microphone transformer in it. For instance, old used AudiTronics 501 & 110 input modules. The later units featured Jensen Transformers whereas the earlier units had slightly inferior factory made Transformers. Still usable however with a similar quality to your 3124. And those include air core inductor equalizers. So also a little like a Neve. You can frequently find those for under $200 per channel. But if you want that nouveau sound? The ones you mentioned would provide that.

I have plenty of those 501 modules for sale. But that's not why I recommended them. I recommended them because they are a close match to the API 312 microphone preamp and because those are a great Bang for the buck. I'm not offering them with power supplies & cabling. But that's a rather simple thing to accomplish if you know how to read schematics & solder. I personally love transformer front end microphone preamp's. I don't like transformer less microphone preamp's. Sure they sound good. But not to me. Not my cup of tea. I find state-of-the-art preamps too impersonal. It's all about character and personality.

A personality character
Ms. Remy Ann David