Old records.

@rvpiano 

probably a combination of things.  I prefer digital but I acknowledge it’s possible to get excellent results with a good vinyl setup.  
  Not all lps from back in the day sound great.  A whole slew of them sounded much better in their digital incarnation.  I know that you listen to a lot of classical .  Goddard Lieberson, who headed Columbia classical during the early lp era, wanted his recordings mixed as though the average listener would be listening on AM car radio.  Most of the RCAs from  seventies had muffled sound and horrible vinyl quality.  Play any CD of an Ormandy recording from that era and then compare the lp.  I could go on but the point is it depends on what lps you are referencing.  In your OP you say that old lps should not sound worse than newer ones, but in many cases precisely the opposite is true.

  Worn out stylus?  The issues there would be tracking difficulty.  However you may want to check the settings on the phono preamp.

  And I believe you are in your mid eighties?  How preserved is your hearing?

Wow! I remember finding orchestral RBCDs from the 80s (which would include Ormandy recordings derived from earlier performances) to be just awful. So bad I couldn’t bear them even at a friend’s house during a party. Massed strings, to which ormandy was no stranger, sounded like crumpling of cellophane. This was on an otherwise high end system using his brand new Meridian CDP.

I live with old, I mean OLD records. A couple things, first, upgrade your stylus to a Line Contact, or SAS, or other nude elliptical (for stereo, and a good mono cart...). Those styli designed for 4 channel (like the SAS) are an excellent choice for 70's and 80's records. The deeper into the groove the better (virgin territory...). Second hand records have an unknowable history, quite often the "top" of the groove has been worn by old, or inappropriate cartridge/stylus choices, or dirt. I also recommend Moving Magnet or Moving Iron for used records until their condition is known. As for cleaning old and used records I use Tergikleen mixed per manufacturer's directions in a Spin-Clean. I rinse with a spray bottle of distilled water, and then dry on a Record Doctor (vacuum) then air dry in a rack for a bit. Tergikleen can be formulated for Ultra Sonic as well, but it must be rinsed with distilled water no matter the method (get some label protectors on Amazon). The PVC (it's PVC that keeps vinyl records out of curbside recycling, nasty when melted) in the record is a recipe of different suppliers and products. Pressing plants often recycle rejects back into the mix. It is impossible to know, unless you mixed the batch yourself, just what is in your record. Some of the component parts of the vinyl mix can react badly to alcohol. It is not worth the risk of exposing your vinyl to any amount of alcohol. I have a ruined Mahavishnu Birds Of Fire LP on which I naively used a home brew recipe cleaning solution that had alcohol as an ingredient. None of the other records cleaned with that recipe show the same damage. The damage is visible through a magnifying glass, looks like ripples in a sandbar (the solvent action of the alcohol removed something and left the record "dried out"), and the damage was probably cumulative. And finally, if you can't think of your vinyl, polystyrene, or lacquer collection as Artifacts, you are bound to be disappointed. Yes, there are some excellent sounding pressings out there, and a perfect marriage of record, stylus and electronics can sound spectacular. But digital perfection is not what record collecting is about, for me, anyway. Maybe you can price your collection (3,000 is not an insignificant collection!  I'm sure there are some gems in there) on DISCOGS and find your nirvana..  Good luck

Interestingly, when I compare Reiner’s RCA .5 mastering LP of the Mousorgsky Pictures at an Exhibition it sonically blows away the Idagio stream of the same performance.  But this is a rarity.  Normally the Idagio streams sound better in comparison to LPs.

LEWM,

I do not want the OP to give up on vinyl this is why I suggested trying his older vinyl on a second system to see if it’s his system or the vinyl. I have spent hours on the phone with JR from WAM Engineering or Wally Tools. I have tested these theories enough that I can change my VTF/ VTA in one minute even though my tt has an Allen set screw on the tone arm post. I just wanted the OP to test some things out to help him out as efficiently and cheaply as possible. I listen to a lot of different types of vinyl but most of my collection is classical. I don’t mind that people are not into vinyl. I do feel when you hear it done correctly it is on another level.