Man...I'm hoping others will chime in, but IMHO the sonic differences in pre's between the mixers you are talking about and/or a Tascam 300-series or
anything in that arena are going to be hair splitting...none of them are "boutique" pre's and neither are any of them ROC special...y'know what I mean? I'd be happy using
any of those pre's but from an engineering standpoint I can tell you that I think you are making a mistake sacrificing good control room and monitoring capability to get
maybe a slightly better mic preamp (based on somebody's opinion)...I'm just basing that admonishion on your priority list:
I'm mostly concerned with getting the best sounding pre's, eq's and mixing and such that I can afford and then I'll make comprimises elsewhere.
You need to ask yourself also what you are expecting this mixer to do for you. It won't make you sound better or improve your skills. I'm not questioning that at all...I don't know you from Adam but I know its a mistake I made. I've heard incredible sounding songs from people on this very forum and they've done it with "second-rate" mics on 25 year old cassette 4-trackers. I'm picky, and I think I can recognize a good mix vs. a bad mix and this stuff blew me away. And I figured if they can do that on that gear then gear is not my limitation and neither will the difference between the pre's on a MixWizard, ZED, Onyx or Spirit M mixer...I can tell you from experience that its an exercise in frustration to use a mixer where you have to jury-rig monitoring functions and patch and re-patch to get the job done and at that point you
and the talent would rather anything with the right functions be in place than something that some marketing guru told the world was "better". That's my 2p but I feel pretty passionate about that and I don't believe you are going to find anything in your price braket better suited for mating with that 5050-8 than something akin to the M-312...
the WZ3 14:4:2 comes pretty close.
And as far as pre's go? Maybe I'm biased/inexperienced/insane, but my
favorite pre's in my studio are on my 20 year old Tascam M-520...haven't used the 308B yet as it needs work but based on the channel architecture and the opamps used I bet I'll like those even better, and that's comparing to a Yamaha i88x (only 2 pre's but they are based on
the Yamaha DM-2000 pre's...Google that...highly touted pre's as were the i88x's in kind) and
a Presonus Digimax FS. Hands-down I like the M-520 better. If somebody was going to
give me my choice of the mixers you listed or minty Tascam M-312B, I'd take the Tascam. It would be a better fit for what I do.
So, do what you're going to do, but knowing what I know today I can't imagine spending $1200+ bucks on a mixer that lacks the things I need in the control room and doesn't sound as good to me as a mixer that's got it all and more that costs 1/3 to 1/4 the money.
That's one opinion but it is based on 2 full and involved CD projects and getting my hands dirty with the internal components and how stuff is put together.