I had my ears checked, and every audiophiles nightmare I have a significant lose of high frequency above 6KHZ, I knew I had some lose, but not at such a low frequency, so I got my audio generator, scope and with earphones, checked and I found it to be about -30 db from 6 to 12KHZ about the same the hearing test found although they cut the test off at 8KHZ and I found I can’t here above 12KHZ, my preamp dose not have tone controls so I can’t turn up the treble, but I do have in storage a NAD 1300 preamp that has tone controls, in fact they are the parametric type that will allow me to adjust frequency’s at +12 db between 6k and 12 KHZ I didn’t realize how much treble in music I have been missing, I’m 74 years old and the hearing doctor told me this is about normal for men my age, I could get a hearing aid to help with high frequency, but if you do it for music you may not like the results, apparently hearing aid are not HiFi I’m not sure what I’m going to do about the NAD preamp it doesn’t have balance outputs and because the power amps are 20 ft. from the preamp this would be a problem, so I will have to interface the two preamps for the time being, anyway if your getting up in years you may want to look into a hearing test.