Paragon 12 preamp; need to know tubes in linestage

Here's what I would do. Play your source. Keep gain set low on amplifier. Turn off preamp. Take out one tube. Turn on preamp. See if source still plays. Repeat process one tube at a time and see which ones can be removed without stopping the sound. Replace the ones that are necessary for sound from your source.

No, not a good idea to run a preamp without all of the tubes in place even for a moment. They present loads within the circuit. You wouldn't run without a resistor or cap, would you? Damage can result. Any tech should be able to look under the bonnet and tell you in a split second what's what or, if you have confidence, why not just sub in your new high end tubes. If you sub one in and you can't hear a difference then either it's not in the line stage or, if it is it doesn't matter anyway 'cause you can't hear the difference.

Neal - I used to be a dealer for this preamp when I had my store in the late '70s. If you care to send me your 'phone number, I'll call you during my "free weekends". Pretty sure I have a piece of literature on this unit. Don

If you have the unit facing you - and look down from the top - the four tubes to the farthest RIGHT (count from the right side toward the left) are the Linestage tubes.
-Mark

And BTW, you can pull the four phono tubes and it will work fine.
Mark