I lived with one of these for two years. It’s a very nice DAC. Quite a bargain, for the sound quality. The ergonomics and buttons are aesthetically pleasing. I tried it out in different configurations, but finally decided not to use it as a preamp, keeping it for the DAC and CD’s. I replaced it only when I was able to quadruple my budget.
As a DAC/preamp, it sounded great and very neutral to my ears. The biggest thing that kept me from using it this way was that I really, really like a volume knob. An actual knob. I would have much preferred a CD100 in this regard, but I bought the CD50 before the CD100 was released. I also felt that there may have been a limitation in voltage output. I only used it in the unbalanced mode. Maybe it would have more ’overhead’ in balanced mode, or with a higher gain amplifier than what I was using.
I’ve heard that you should be gentle with the RCA sockets, but personally never had a problem.