John,
A couple of suggestions. First, I have found that sometimes harshness doesn’t always eminate from the frequency range you think it’s coming from. I would try attenuating the midrange by trying the resistors there, and maybe put your nice copper jumpers in the tweeter spot. Or, maybe both tweeter and mid-range get the resistor treetment, or both get the copper. Whichever way sounds best. Sometimes it just takes a lot of little steps.
Second, I’m glad to hear you’re going to test the record when your system has warmed up. You’ll probably have to test records one day an you CDs on some later date.
I might suggest you turn on all of your equipment and let it all warm up for 45 minutes, as you usually do. Play just one side of a harsh sounding record (your Elton John record seams like a good candidate), and note the harshness - where it’s most noticable, how loud, etc. It would be good if you had a second pair of ears to verify what you are hearing. By the time you finish the album side your equipment will have been running about an hour and 5-10 minutes.
Now, try not to change the volume setting, or any other setting, and play another 3 or 4 album sides worth of music. Play a different album or two until your equipment has been running for a total of about 2 1/2 hours. It would be better if you had other things to do and left the room. That way you’ll have a better memory of how the harshness initially sounded and your ears won’t gradually get used to the sound of your stereo if it changes. (Also, don’t keep playing the Elton John album. Repeated playings of the same record could introduce new distortion). While I’m at it - no alcohol or other perception altering activities. Sex with the wife is OK though. Just tell her it's for science.
After your equipment has been playing music for a total of about 2 1/2 hours, sit back down and listen to Sir Elton again - same side as earlier. Noting the distortion or harshness - is it the same? Is it different? Has it improved?
I would also repeat the same test a few days later, using an offensive CD and sticking with CDs throughout the test.
I’ll be interested to find out what you hear.
Tim