Does this mean that, if you used a non-valve amp, you'd also have an unwanted D/A conversion, as with a digital FX box...? (Because I was also thinking of taking the signal through my Ashdown bass amp and using the DI from that.) Would there be a difference between using a valve amp as a "pre-amp" for an electric guitar and using a non-valve amp...? I know people are very choosy when it comes to vocal mic pre-amps, but I haven't noticed the same attention to detail for DI-ing guitars.
Re: active v passive pickups, this was also in the back of my mind, as I've seen conflicting advice re: running active pickups into a Mic socket.
And now you're saying it also depends whether you use an active or a passive DI...?
D'oh. I need to read a book.