Please Help: Onyx Situation

I'm about to purchase a Mackie Onyx 1620 for use with my Mac. I was recently looking at the product when it occured to me, "What use do I have for all the knobs on this damn mixer if that's what I have the computer for? I mean, I'm only using the mixer for the preamps, not the EQ or any of the other stuff I'm paying for." Is it still worth buying?

onyx preamps

more specifically the 800R.
How's the quality on these? Any users here?
My MOTU 828II is officially full, and I will very soon need more analog inputs and this seems to be a nearly perfect solution to that and the selling off of my Focusrite TT Pro. I hated that preamp, horrible compressor, and "EQ" unit, and I'm glad its gone. My MOTU pre's sound just as good.

Problems WITH ONYX/CUBASE.

Im having problems with the onyx firewire and cubase. . after installing everything when i hear playback it glitches and i hear little pops and then i squeals. .i tried adjusted the latency settings but it doesnt work...someone told me it was a digital clock problem but i even tried changing the sample frequency. the audio doesnt work in audio or traction correctly.

ONYX PreAmps.

This may come as a subjective question to some but I'm looking for some opinions. using the at4050 mic and the preamps in the onyx1640 do you think i should still use a good preamp? As well as with my keyboards? I doubt i need to run my mpc through a preamp? Advice is well taken!

Onyx pres alongside a ISA428?

Looking to increase my inputs to accomADATe more live recordings. Currently have a Focusrite ISA428 into a Motu2408MKIII and we're looking at adding the Onyx 8 channel pre. Wondering if anyone here has experiece with it and how it might mate with the ISA.

Will most likely be used heavily to mic drumkits and some other instruments.

Respect...
LRG

PROTOOLS AND MACKIE ONYX

Increasing fidelity and system fliexibility is the need of the hour.

My work and my investment requires me to be capable of handling the following audio situations.

1. Studio recording with 16 simultaneos tracks at 16 bit 44.1 Khz.

2. Live recording with 16 simultaneous tracks preferably thru a compact source like a Firewire into a laptop.