I was looking at the 24 I/O and the various retailer webpages just switched from listing current prices to describing it as no longer available.
 
The MOTU web site has been changed so that it no longer has a current "PCI Audio" category.
 
Crazy times.

I'm not hugely surprised. As I noted in the other thread, they are kinda Mactarded. Well PCIe is gone from Macs. You can't get it in iMacs, but now you can't get it in the new Mac Pro either. Some companies would say "Oh well, silly decision by Apple, we'll keep making it for PCs." MOTU seems to have said "We follow whatever Apple does! No PCIe!"
 
That said it isn't as big a deal these days, modern processors can do pretty low latency over USB, particularly USB 3 if implemented properly. Still though, PCIe is nice because it is the system's actual bus. For that matter if you don't use a discrete graphics card you can stick a card in the 16x video slot, which hangs right off the processor and doesn't even go through the southbridge.
 
Something you could also look at is Focusrite's RedNet stuff. I dunno what it costs, but I've liked my Focusrite interface. The Net card hangs right off the PCIe bus, of course, and ethernet is exceedingly low latency (packet latency is around 100 microseconds on most networks, and that is with all the TCP overhead, which you wouldn't have with their audio only system. It should add a totally negligible amount of latency over the converters and buffers.

Sycraft
That said it isn't as big a deal these days, modern processors can do pretty low latency over USB, particularly USB 3 if implemented properly. 

I think it is this idea that is going to leave us hanging without the good solutions we use to have.
 
There are no companies offering a 24 analog I/O that runs at 64 sample buffers over USB.
 
No one offers 24 channels of 24bit 96kHz over USB at low latency.
 
The USB stuff seems great until you want to use it too outperform what you could do with PCI and then you find out no when has pulled that off yet.
 
I am su****ious of USB as a long term audio bus solution because I have concerns that my system is using all sorts of other stuff as USB and the juggling of priorities must be a nightmare and I can't see it getting any less so.
 
It's not like my querty keyboard, MIDI stuff, or E-licensing is being updated to run on PCI-e to make room on the USB bus for uninterrupted audio streaming.
 
I think the USB audio "revolution" is being fueled by optimism and the fact that usb appliances are cheaper to make than any other choice the manufacturers have.
 

Sycraft
I'm not hugely surprised. As I noted in the other thread, they are kinda Mactarded.

 
I was looking at the Apogee stuff for a short while until I figured out that they don't even pretend to support Windows. :-S
 
 
 

The new MADIface XT USB seems to be a fairly new exception to what I have said above about 24 channels of 24/96 I/O...
 
... but it looks like another $10k solution.
 
$2695 USB MADI I/O.
 
$5000 - $7500 for analog to MADI gear.
 
 

RME charges a ton because they can, I think. They seem to be way better at hardware and software than most pro companies. They do better USB implementation, write better drivers, and hence get great performance. So, they charge a ton.
 
The reason I'm optimistic that USB may improve in the future is USB3. For one thing it just has more bandwidth which means more audio channels, but also lower latency. The faster your bus, the quicker you can transfer data and thus lower latency. Equally important is it can do DMA, Direct Memory Access. This means the device can write data right in to RAM (as PCIe and Firewire devices can) bypassing the processor. This leads to lower system load and of course lower latency. Finally it is full duplex, which means no contention when doing simultaneous IO.
 
Now for any of that to matter we need companies to support USB3, a USB2 device doesn't get any better plugged in to a 3 port, and we also need companies to do a USB3 implementation that doesn't suck. Audio companies are not so great at that whole "not sucking" part so it could be awhile.
 
As I said, maybe look at the Focusrite Rednet stuff. Another option could be three RME Multiface IIs. RME gear can run multiple units in a system and sync. That'd get you 24 analogue IO, plus another 24 ADAT. Doesn't support their newest Totalmix FX stuff, though that is supposedly being ported to it, but without all the effects (since it lacks the DSP for them). Not cheap but $3k instead of $10k. You would need 3 PCIe slots though.

I used the 24IO for years with great success! Sadly, I had to move up to something that had more sync capabilities. It really broke my heart to retire it. I ended up making the investment in to 2 Studio-Captures. I am very pleased with the results I've been getting with them. I was afraid I was going to have to give up the low latency of the 24IO but the Studios have matched it bit for bit so far. Still, I am tempted to pickup a PCI-E card somewhere.

Thanks for mentioning the RedNet. I didn't know about it, so I just went and checked it out.
 
FWIW 24 analog channels of RedNet I/O costs about $7k.
 
RedNet 2 at $3k
Rednet 1 at $2k
Rednet to PCI-e at $1k
DB25 breakouts at $1k
 
The discontinued MOTU 24 I/O at $1.5k is looking better and better. :-)

The new MOTU stuff uses thunderbolt, you can get a thunderbolt PCI card for around $150.
Why not just go that route?

Re: Post #2
 
No Windows drivers for MOTU Thunderbolt.
 
When/If MOTU puts out Windows drivers MOTU says it will be Windows 8 only.
 
http://www.motu.com/products/avb/16a/specs.html
 
 
I only put my Win XP machine into semi retirement recently and when I bought my fancy new Win 7 x64 machine last year I was disappointed to learn that the MOTU firewire drivers for Win 7 had close to twice as much latency as the Win XP drivers for the very same hardware.
 
I don't want to set up a Win 8 machine just to find out if there is an improvement over my old Win XP machine.
 
 
Progress...
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                  ... 

After having a bad experience with my MOTU midi interface many years ago (unbelievably it has functionality that you can access from the front panel but only actually configure to be able to use it from a Mac, and they never ever bothered to add it to the Windows side), I decided I just won't buy from "Mac first" companies for use with Windows.