Could you recommend a nice used USB DAC?


I am looking for a nice used USB DAC.  I currently have an Arcam CD23 which I really like to but I am looking to go with the USB DAC route for high resolution streaming. 
Could you recommend one and give a short description on the sound?
It seems like there are a lot of recommendation for the Chord Mojo DAC but it seems to be a bit more on the "detail" so I am not sure it would be for me.  The reason I like the Arcam because although it has a lot of details, the musicality always comes first.
andy2
if you looking just for a USB input DAC, go for BorderPatrol DAC, its flying under radar, and very rarely you will find it for sale used anywhere online. Ask any senior / seasoned audiophiles, it is as good as $5-7k Dac for just $995 msrp. 

I used to have that Cd player years ago. The FMJ, full metal jacket. My sister bought it from me, I now use the Aloia for cd's.
Scott Nixon usb tube dac new is what I'd recommend.  I’ve been using Nixon tube dacs for years and they’re very affordable. I've never heard anything better. Legends...

http://www.scott-nixon.com/dac.htm
I just put in an order for the Ayre BQ-9 DSD.  Hopefully will get it soon.