I'm guessing bhuard75 is thinking of a power-amp-only device, though my impression is other manufacturers who do that usually started with a separate preamp rather than the other way around. That said, the Synergy amp basically has this covered already with a Diezel preamp module available, so it would probably be redundant. But it is educational taking other preamps and putting them through your Diezel's power amp via the effects return. I did that with a couple AMT tube preamps going into my VH4 last year. (SS-10 and SS-11.)