From the extreme of an amp with a 470kOhm grid leak and a pentode gain stage to a Sakuma-style 845:845 amp or step up TX coupling. The load on the linestage is going to have some effect on the sonics, and will depend on the ability of the pre to drive a difficult load.

So, where is the line in the sand, or is it a broad smudge? Of course cabling can contribute to the capacitive load on the pre....

I suppose one answer would be to use the pre which can drive anything. These are usually either complex or 'spensive.
regards,
Dogulas