Sycraft
If you are sold on a PCIe bus card for the lowest latency, you could look at RME's HDSPe MADI or HDSPe MADI FX. You'd then need a converter box, of course. Not a cheap option, but should be real low latency, nto to mention extremely flexible.
When ever I look at the RME MADI stuff I walk away thinking that it would be cool, if I already happened to own a $40k console that happened to have MADI on it.
If RME happened to have an affordable 24 analog in converter to go with the MADI i might get more interested. The $5k M-32 IN seems pretty cool but I'd end up with a $9k package before it's done.
I have yet to find a 16, 24, or 32 IN channel all analog package with a few built in OUTs, all running off a internal clock that makes affordable sense for me to go MADI.
The LYNX 16 runs great without MADI and it's affordable and has a internal clock... but it's only 16 channels.
The Antelope Orion is 32 channells on an internal clock but it has a minimum sample buffer size of 128 and if you want low latency they advise you to record at 192 kHz.
The BURL mothership seems kind of cool but I think I priced it once and I got to a $12k package very quickly.
The rest of the stuff seems to take you down the road of having to use a bunch of wires to clock everything together and then you can spend the rest of your life wondering if your clocking is as good as it can be.
I know my specific interest of having 24-32 analog in all on one system is rather "niche" but it seems like in 2014 the technology is there.
The 24 I/0 is a great form factor but as I say it has a reputation for leaving people wishing they had the latest technology inside it.
I was about to snap and buy the MOTU HD192 system as the form factor is very close to ideal for me, (If I gnore the reputation for the cooling fan going berserk) but the guy at MOTU tells me, quote:
"We do not support the MOTU 192HD anymore" and I say
"But it still sells new at full price..." and he says,
"Yes, we do not support the MOTU 192HD anymore".
The Antelope is a great form factor but it doesn't seem to have a great driver and the warranty of only 1 year and a potential trip to Bulgaria for service has me in a holding pattern on that one.