I want to build a 5F2A with a 6SL7 for the preamp. This will be a slow learning process for me I am wanting to use this as a try at drawing tube load lines for the 6SL6 tube. This would be the next quantum leap for me opening the door to ursine all kinds of tubes or just getting the commonly used tubes dialled in. I am using the most excellent information provided free of charge by Rob of Robrobinett fame. https://robrobinette.com/Drawing_Tube_Load_Lines.htm So the data sheet for the 6SL7 gives a max plate voltage of 300volts. https://frank.pocnet.net/sheets/049/6/6SL7GT.pdf below it gives an operating voltage of 250 volts. In an ideal setting would 250 volts be a good starting voltage to use. I want to amp to have some nice dirt on it and don’t want to set up the preamp tube to be clean. So would 250 volts get me there or do I want to start with some other voltage , like going t to the 300volts being a guitar amp. Cheers Ron.