So ehere is a good place for DI in valve amp.

[diydidi]

I have a request from a client. Its a 200watt bass head. No schematic as it is boutique job.
He wants to add an internsl DI to it. I can build the Di with some opamps etc. Where is a good place to tap it off from?

[Enzo]

What does he want it to do? Some take it off after the input stage, usually before any preamp controls, so it is pretty much just the instrument heading to the sound mixer. Similar to a tuner out. Others take it off from the output, so that whatever changes the player makes in the amp will also appear on the DI. Then also arises the choice pre or post EQ. Pre or post MV. and so on. You need to find out how he intends to use it. There are examples of all of those in various makes and models.