@mulveling Great information, thanks. I guess the Steelhead retrieves detail sufficiently, does most things very well, but doesn't imbue the sound with the typical midrange bloom and presence that I expect from tube gear. It's a little bit solid-state sounding, as others have alluded to here and elsewhere. @whart above describes it as 'a slight electronic glaze', which I think is a fair assessment, with emphasis on 'slight'. It hasn't responded particularly well to tube-rolling, the tubes I've tried haven't really tilted it away from neutrality to something with a bit more bloom.
With this in mind, I've been reluctant to try an ARC phono as my experience with their preamps and power amps over the years has left me with the impression that their gear is voiced a little on the lean side, a little neutral perhaps. Maybe I need to reassess.
Cheers
Rooze