Help- Denon DP59L...

Glad to hear that you had some success, and learned some of the things you need to know about analog. That was a good step. If you have other questions, please ask, and we will be happy to help if we can. There are any number of members who could give you the answers you need. Everybody has to learn as they go along, and nobody knows everything. I have had alot of help from members with my questions, and I try to help others when I can.

Thanks for the tough love. Acting on Twl's advice I am attempting to lear about this alignment stuff. I purchased a tracking force gauge and adjusted the tracking force upwards, but not too much upwards, which completely solved the problem. Now I am trying to figure out the VTA and some other settings. This analog stuff sure is a lot of work...I mean fun.

Does the dealer who sold you the new Grado cartridge and set up the table have an explanation? Does the dealer offer other brands of cartridges besides Grado? Did you buy the table from this dealer? The Denon is one of the best DD TT (doesn't cog) so I would go to the dealer first before replacing. That's what you paid him for....

It sounds to me like there could be some VTA things happening with different thickness records. That could cause "ssssibiblance" problems. I don't think that there is a VTA adjustment on the Denon.
The adjusting of settings on a TT is something that an analog user must learn to do himself. First of all, in this era of digital, there are very few "experts" left on TT setup. The guy that set up your TT may, or may not, be one of them.
Secondly, when you transported the TT home in the car, there is a possiblity that the tracking force was slightly moved during transport. Actually the counterweight should be removed during transport anyway, to reduce possibility of damage to the tonearm bearings from heavily loaded vibrations. So he should really have instructed you how to do the tracking force, and removed the counterweight before you transported it home. This leads me to believe he is not an "expert". Therefore, any adjustments he made may have not been made correctly by him, or may have changed during transport. If he even listened to the TT after he adjusted it, is unknown.
How about asking us how to set up the TT? I personally have set up hundreds of high end TT's of all kinds, for many high end systems, during my employ in an audio salon in the 1980's, when analog was still in it's heyday.
Next, and I know you don't want to hear this, but the Denon is a decent Direct Drive TT, but it is really a marginal performer at best. A simple Rega P3 with RB300 would walk all over it. Stay away from Direct Drive unless you're buying a Rockport.
What you have, is a nice entry level TT, that is good for getting your feet wet in analog, but not good enough to really reap the benefits that analog can provide.
A simple question on this forum about whether to buy a DP59L or a Rega P3, would have saved you this headache.
All is not lost. You may still be able to adjust the sibilance out of your TT, but it will not take you into the "audiophile" area of analog.
I know this is hard medicine, but somebody has to tell you, or you will keep spinning your wheels, and get disgusted with analog. That would be a shame, because there is much to be gained there. Just trying to help.

P.S. - When you sell the Denon, sell the Grado with it, if you are going to get a Rega. The Grado cartridges have hum problems with Rega TT's. Get a Goldring 1022GX. And when you get the Rega, order a VTA adjuster from Expressimo Audio for $39.95 to put on it.