I would be tempted to try Bill P's solution. At minimal cost you can convert your USB output to optical and use the optical input on the Leckerton. Look back at his posts and you'll find it. I haven't heard it myself, but in your position and for the price I would certainly try it out.
Thanx a lot. But there's something going on with that conversion ... namely some noise or something else is introduced. It ain't so perfect.
Perhaps, one needs an expensive converter. That's what I've read here and on some other audio forum.