Not exactly that specific combo, but I've played with variants.

I heard Steve's prototype, and my Zen Mystery Amp basically has one built in (it's basically the Jensen 1:1 transformers and a volume pot). Plus the ZenCD has one built in as it's unbalanced output - and I've played with all three.

I feel the transformers add a nice sparkle to the sound, and the Decware amps in general like the higher voltage that can be obtained from balanced output to a unbalanced input.

Assuming your source (like your Oppo, which I have as well) has a proper balanced output, then you'll really like what the ZBIT does with your Decware amps.