Thanks for all of your feedback. I'll check out these different options.
The F7 arrives tomorrow, so I don't have a preamp for it yet. I've got a Freya S downstairs which I'll try for a bit and maybe stick with that if it sounds ok. I use that currently with a 300b integrated for more inputs and volume control (I run it in passive most of the time, buffer mode some times).
I've had an F7 before for a short while which I used with a Freya +. It was an ok combination, it's honestly hard to remember. At the time I was using Zu Soul Superfly speakers which were high efficiency, but not my type of sound. So when I sold the speakers I sold off the whole system more or less.
I'm interested in the Quicksilver, Van Alstine, and also read good reports about the Wyred 4 Sound STP-SE if anyone has experience with that.