Turntable sound bad


I have a Rega rb250 with mitchell technoweight, vta adjuster, dnenon dl 103 cartridge. A Rega Planar 3 plinth, with aftermarket steel spiked feet. The problem I am having is setting it up to sound right. After the first few songs play, the voices start to sound hissy, and progressively get worse toward the last song.

I am wondering what would cause this: turntable being out of level, Vta, cartridge overhang, Tracking weight? Obviously I am not doing something right, and this is way beyond my limited knowledge. Oh well I hope someone out there can direct me what to try first. Thank in advance, Jason.
jasonh37
Thanks for all of the response. I am confused I thought that spiked feet, where only 1000ths of an inch is touching should isolate better than the sorbothane feet. I am using a Musical Surroundings Phonomena for my phono stage, set to reccomended settings from M.S. rep. I have read that the Denon cart was a good match for the Rega arm. I will try the re-allignment of the cart first, for I do believe that might be the problem. I will let you know the results.

P.S. I do believe that the table sounded the same with the stock feet, but I will do a comparison to see if there is a difference.
Based on the OP description it's highly unlikely anti-skating is the culprit.

It seems like a simple case of mis-alignment.
Antiskate needs to be checked after you are certain the table is 100% level. Use a test record with a grooveless section. Be certain the arm will float with neutral weight to the spindle and to the arm rest, thus checking the bearing laterally. Clean the records well and the styli....jallen
Agree with Narrod and Viridian on both cartridge alignment and the arm/cartridge match. Here's a link to the HiFi mod . Mandatory reading for most Rega/OL tonearm owners IME.
Post removed 
Stringreen, I'm glad you like it. I've heard that table with about every type of support imaginable and always prefer the stock feet. We all don't hear the same. Whatever works for you is correct.
Narrod, Viridian, I disagree with both of you regarding the feet. On my Rega 25, I put Cardas blocks under the unit which bypasses the feet, and it made a huge difference for the better.
Viridian, agreed, removing the stock feet is a recipe for disaster with this table. Those feet are tuned for the table and provide the best support/isolation for it. I don't think that is the core cause of the problem scribed.

Wendell
Post removed 
What you describe is normally caused by a misaligned cartridge - 11-28-08: Narrod

Yes! You need to re-check for correct cartridge alignement
You should have the Rega paper template for this
Redo you cartridge setup or have somebody who knows how to do it. What you describe is normally caused by a misaligned cartridge. Good luck.