Edit: Just looked at the link for the USB-32 upgrade in the NFB-7. He seemed to have upgraded from the Tenor TE8802. Unlike the TE7022, the TE8802 has it's own daughterboard. For him, it was only a matter of switching boards. For me, I'll have to see if I can find a place to put the board where there wasn't one originally... hmm.
Quoting myself just to point out that I misread the NFB-7 USB upgrade post. The original NFB-7 did not have the TE8802 - it's too old far that. It seems like he replace an entire board, but I'm not sure what that entailed as I've never seen the inside of an NFB-7. But certainly different from upgrading to a USB-32 from a TE8802 board, is I speculated.
Anyway, I've gone ahead and ordered the USB-32 upgrade kit for my NFB-10WM, so we'll see how that works out. If anyone is interested, I can report on my experience with the upgrade process. Kingwa said I could just stick the new USB-32 board on top of the no longer used USB section of the DAC board. I'm thinking I'll just use some double sided tape and some insulating material in between, but I'll see if I can't come up with something better.
I'm really clueless as to what kind of change in SQ to expect. I did notice a slight improvement in SQ using the original Digital Interface for USB, vs the native USB that came with the NFB-10, but for most music, it was minor - a little more accuracy and separation and less congested sound. On the one hand, I've read that the WM8741 is less impacted by power topology vs, say, the Sabre or Burr Brown multibit DACs, I don't know much about it, but this might be why Audio-gd doesn't offer it in more expensive gear. Or it could just be that it is considered the inferior DAC (which I guess most do). It definitely is cheaper than the other DAC chips. On the other hand, the WM8741 lacks the native jitter correction as the Sabre DAC, so maybe a better USB implementation will make a noticeable difference? I'm not holding my breath though.
The USB-32 upgrade kit was $54, or $80 with shipping. Probably not "worth" the money, but hey, should be a fun little project and might even help retain some resale value for the NFB-10WM. But at the rate Audio-gd churns out model updates, there'll probably be a new "best" USB implementation out in 6 months