<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div>Hi Phil,</div><div>Thanks for that, digging further I found that the error was exactly 20dB - a clue! I then tried setting the preamp button to on, voila all the indicated levels were then within 1dB!</div><div>So I think 'preamp' for hermes means 'attenuator off'. On my board I haven't fitted the Minicircuits digital attenuator hence the problem!</div><div>All makes sense now!</div><div>What is the ADC button for?</div><div>Thanks,</div><div>Andrew<br></div><div><br></div><div></div></div></body></html>