The Kingrex (now discontinued) was good up to 192/24 although at trade shows, using Jim Salk's streamer and computer source material, we were only playing 44/16 and some 88/24 material. We used the Kingrex mainly because Jim's streamer only has USB output and we needed to support that with our DAC.
Right now I am evaluating the new USBstreamer board from Mindsp. We have it running just fine on 192/24 material on my engineer's PC using the solftware download that comes free with it. However, it is giving us headaches with my new Macbook Pro computer. It should run fine with it with no drivers needed at all, but we get everything out but sound. I need to try another music program. I am currently using Fidelia and the USBsteamer is not working with that at all right now for some unknown reason. This is driving me a bit crazy so far.
Note that with the jumper connected both pins in an AVA DAC, all bit rates will play just fine. Technically, in that mode the digital filters are not optimized for 44/16 playback, but in listening here it still sounds just fine with the jumper set for high bit rate. There will be some roll off above 16,000 Hz, but if you can hear the difference you have a lot better ears than I do.
Regards,
Frank