Pan American horns are very hard to research, because a lot of the information and records were destroyed about the time Conn was purchased by MacMillan in 1969. Pan American was made by Conn, and was Conn's second line. There were few sopranos made. Most were either alto or tenor. My guess is that your horn was made between 1922-1924. It's basically the same horn as the Conn New Wonder Series I curved soprano. As for value, it really depends on the condition. Chances are if it has been sitting for a long time, it's going to need pads, and most likely an overhaul. This can be quite expensive. The later straight sopranos had better intonation than the curved sopranos and are typically more valuable. I am guessing that a complete horn with no dings or dents in the body; minimum key wear and no damage, your horn is worth $350-$500. If it were cleaned up and made playable; maybe $900-$1000. That's just an educated guess.