Can't beat the price I suppose since some are $25-$30 and simply have a couple sets of RCA's on them.
Since I"m a gadget junkie though, I tried a few of these I have floating around.
Just your cheap basic USB sound card with 16 bit 48 Khz sampling.
The funny thing is, you can connect a few of them and each one is identified by your general recording software and serve as a 2 input source meaning multitrack recording!
Obviously you're not going to use these to build a reliable studio but it worked surprisingly well without latency. I've stacked 2 of them for 4 tracks of recording and without latency.
Just a cheap option for say the garage band kids that have 4-5 band members and need a dedicated track for each. This will give you studio grade results granted your PC can keep up with so many tracks.
I know it does get to the point that you need some heavy duty hardware when you start getting into 8+ track recording. Just for fun, I'm going to run 4 of these into a USB PCI interface and see if it can pull it off without latency.
My last contribution in this thread will be these larger modules with fiber optic interface. Considering what Behringer sells in the $25-$30 range which are the cheapest and most basic USB units being sold commercially, these are certainly worth the risk once you've compared.
Just under 15 bucks and it has the juice to run S/PDIF AKA a fiber optic chain. That means 24 bit 48 Khz analog conversion. Granted you have the hardware to connect to it. While they don't use RCA connectors like the Behringer units...they still look a lot higher quality. Comes with what looks like a nice thick USB cable too.
While I have some killer Behringer gear, I've also had some Behringer gear I wanted to kill. All the $50 and under USB interfaces sold commercially look pretty bad to me.
I'll give one of these Asian modules a go sooner or a later and share the results.