denon dl 103 w/ origin live silver mk II: help

I recently purchased a rega p3 with a origin live silver mk II tonearm mounted on it. It is hooked up via a musical surroundings mk I preamp. I had previously had a planar 3 with a denon DL 110 and was very pleased with the sound. So with the new deck I figured that I should go with a new cartridge. Enter the denon dl 103. No matter what I have tried (changing load settings, adding mass to the head of the tonearm), nothing improves the sound. It is shrill, sibilant, and fatiguing. I have had quite a bit of experience with mounting cartridges and always produced excellent results. I have been very pleased with rest of system sound wise. Is it just a bad match with my tonearm or do I just need to let it burn a lot longer. Suggestions???
I am going to assume here you are referring to the standard, current DL103. The Origin Live tonearm's effective mass is marginal for a standard Denon DL103. It's a medium mass tonearm with 12g effective mass. The stock DL103 will perform more competently in a tonearm with effective mass in the range of 15 - 20g. Aftermarket modified DL103 products like the Zu 103 work in Rega-like tonearms of the same effective mass by re-bodying the stock 103 with a more massive and resonance-controlling case. In the Zu instance, their 103 weighs 14g. A stock DL103 weighs only 8.5g. On Rega-like tonearms, the heavier body generally requires an alternate heavy counterweight, too.

You have some choices: the easiest is to simply add mass at the headshell as part of the cartridge mount. You can buy shims of various weights. In your case, you will want to add 3 to 6g, which will put the combination of your cartridge and tonearm well in the system's resonance sweet spot. Right now you have marginal system resonance for favorable performance. You can model your variables on vinylengine, but you have to remember that since Denon measures dynamic compliance by a nonstandard baseline, yuo have to convert their figure of 5 to 9 for use with vinylengine's calculator.

Now it's possible that there is something else wrong, from the cartridge's cantilever suspenstion being worn to insufficient tracking force. In that tonearm you probably need to set VTF in the 2.5g - 2.8g range.

Properly set up, a DL103 cannot sound "shrill, sibilant, and fatiguing." It can be accused of other traits but not those. If it sounds like that, there's something wrong. You have a problem with resonance optimization, failing cartridge suspension, improper setup wrt VTA and geometry, or there is a turntable problem inciting the shrillness (bad main bearing, rattling tonearm bearings) that the cartridge is simply playing back. A DL110, is on the other hand a very good dynamic match for a Rega-spec tonearm, hence your good experience with that in the past.

One thing I'd try doing first if you don't have any more accurate means of testing VTA is just see how low you can go with your VTA and just slowly work your way up. I made the mistake a while back trying to work out the same problems, apparently the cart just needed a couple more degrees down and problem solved. This was way lower than I thought I would be needed but that assumption put me through a couple months of struggling with set up and was wrong.