They are the best for your money. The converters are the same as ADATs for sure.
The preamps are quiet and sound pretty darn good. I use one in a semi pro studio and
would buy another.
Know this:
They are designed to take 8 channels and send it out the adat optical port. And in turn, take 8 channels from your adat optical sound card and play them back analog wise. Beware that out of the box, you cannot get analog output from your analog input (realtime analog preamp mode) unless you jump the adat optical output back into the adat optical input. This is trivial, however in this mode you cannot then send adat optical data to or from your sound card because the optical ports are occupied by the jump.
I run mine to and from a adat optical sound card and monitor the mic inputs with a hardware mixer
before the ada8000. So I don't hear the latency from the conversion and asio buffer delays. (There is no realtime monitoring function in an ada8000 in adat sound card mode. you must wait for the signal to come back from the daw after conversion and buffer delay)