What sort of long term plans do you have for a balanced preamp? I've
been using balanced line stages for a while, and while it is heavier on
parts (double everything) it is easier on the volume control in the
sense you can use a simple shunt stepped attenuator on the output - I
personally don't mind a 12 step one for domestic listening, though
others are more demanding. I happen to use directly heated triodes, but
you can build it or buy it any way you want. One use of a balanced tube
line stage is that it can function as a tube output stage for a
differential DAC board, which is how I use it. The signal from the DAC,
with DC on it, goes direct into the grids of the line stage, which is a
differential pair with a constant current sink under it. This
arrangement works very well and can be made to sound excellent - after
the tube stage choice is cap coupling, transformer Push Pull or
parafeed. All can give you good results. Something to ponder on. Andy