If you're connecting via USB to your DAC, then I would not expect you'd see much benefit. They might reduce noise a little, but your DAC is going to have complete control of the clock since USB passes data asynchronously (at least any virtually all relatively modern DACs).
I think the benefit of the DCC (particuarly the Gaia) would be to take advantage of it's very accurate clock, so you'd need to use a connection that passed the clock along with the data (SPDIF, AES3, I2S).
I think the benefit of the DCC (particuarly the Gaia) would be to take advantage of it's very accurate clock, so you'd need to use a connection that passed the clock along with the data (SPDIF, AES3, I2S).