Behringer Ultramatch Pro SRC2496 by aclarson
I picked this up a while back when I had my M-Audio Delta 1010 to get two more channels on my S/PDIF interface. This box allows you two A/D and two D/A at 16, 20 or 24 bits, and at sample rates up to 96KHz.
This thing has worked perfectly since I bought it. It has lots on connection options -- there's S/PDIF RCA, AES XLR, or ADAT Lightpipe connections available for both digital in and out. Only XLRs are available for the analog ins and outs, but this shouldn't be a problem for most studio setups. Meters are very useful and a nice touch.
Sound quality wasn't perceivably better or worse than my interface converters. I did a comparison between this, a Focusrite Saffire and a Presonus Digimax FS, and all had comparable quality; very clean, but not particularly exciting. All sounded somewhat frequency limited when compared to my PCM4222 A/D. But for the price, this converter is the perfect thing if you need an inexpensive way to add a few channels over a spare digital connection. I haven't seen anything else on the market that's comparable for the price.
Our of curiosity, I opened this thing up to look at the guts, and I was struck by how small the circuit board was. If you look at the case from the outside, the PCB only takes up like 1/3 to 1/2 the interior space. I'd imagine they must use a standard chassis size for a few of their products to keep production costs down, and this was the closest that fit.