It's not tube but I think the Simplifier looks interesting. Lots of options. If it's quieter then the OCSD that would be a good thing.
I think my question for Scuba would be, given he found the preamp a bit lackluster, is it more in the territory of say, a SansAmp, OneControl Sonic Silver or any number of other broad-stroke SVT-style analog emulations that are subjectively more, er, prosumer for want of a better term? Less refined? I wouldn't really push the thing into overdrive, just run it fat clean. If it does that and sounds good, no complaints from me... unless it feels sterile to play. It seems his review hints at that. It did however strike me listening on YouTube that overdriving it sounds pleasant while the SLO in demos exhibits some of that 'can of bees' thing the 12ax7 can be known for.