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.
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.
Sounds like anti skate is off..Too high or too low a setting.......
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
Some thoughts. The Rega template diverges from Van Baerwald alignment. Download the Rega Baerwald protractor from The Vinyl Engine.

The compliance of the original Rega feet is an integral part of the Rega resonance control system. Using spiked feet defeats the compliance of the feet and feeds all of the energy from the stand directly into the thin plinth. It is a recipe for disaster. Get Rega feet and use them.

Finally, the effective mass of the stock Rega arm is waaaayyy too low for the Denon 103 cartridge, though some report good results. A new arm or more appropriate cartridge would be in order, but if this is not in the cards, try something like the TWL mod to add mass to the arm. It is a bit of a band-aid but it should get you going.
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.

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.
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, Stringreen, you are probably both right in that rigid feet make the table much more dependent on the resonant signature of the piece of furniture that the table is sitting on. In my experience, I have never heard anything better than the stock feet as well, but that does not invalidate Stringreen's assertions that, in his system, on his furniture, there is an improvement with non-compliant mounting. However, given the complaints that the poster has, I would be looking at the feet. And the arm/cartridge match, and the alignment and probably the step us as well. The Denon likes to see a transformer for MC gain and does not seem to cotton to head amp gain. Methinks the whole setup is pretty wrong.
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.
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
Based on the OP description it's highly unlikely anti-skating is the culprit.

It seems like a simple case of mis-alignment.
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.