RB300 tonearm cable upgrade?

I have a Rega Planar 3 with the factory supplied RB300 tonearm and microbenz silver MC cartridge. I have heard that the RB300 is a very decent tonearm given the price, but I am concerned that the cable which is supplied with the tonearm is poor quality and doesn't have a ground wire like most of the better quality arms I am familiar with. I have recently purchased an Aloia 13.01 amp which I will mate with my ARC SP-9 and B&W 802 Matrix 3 speakers. I use Kimber cable (biwired) and Tara Labs interconnects. Any opinions on the cable issue? Should I consider spending money to upgade the cable, change to a better tonearm, or look at trading the entire turntable for a better table such as the Rega 9.

I would appreciate any feedback. Thanks,

Lauerman Imports, Rega's importer offers the Icognito Rewire upgrade and they'll honor your warranty if they do the install for you. It is Cardas litz wiring and it's been favorably reviewed in a number of pubs including Michael Fremer in Sterophile. Also I think it only costs like $2-300. Good luck!
I 2nd the Incognito wire above. Also, Galen Carol audio has Origin Live wiring mods, including a Cardas DIN connector which fits into the bottom of the arm post. He also has on a special sale, the Audience phono cable with DIN plug to fit. He can do the installation too. I think that he has the Audience cable at around half price. Don't know how long the sale price will be offered.
Personally, if the cost is $200-300, I would trade for a better TT. The tonearm is already the best thing about Planar 3, and blah, blah, blah. But I am not clued in on the practical side of your potential upgrade, so I take my opinion for whatever you think it is worth.
Just to address the other part of your post, if you have no hum in your system a ground wire on the arm will be of no consequence. Both of the samples of the RB300 that I have owned have been uniquely free of hum with both MM and MC cartridges. That said, the cable does seem to be the limiting factor sonically.
Also, I might add that setting the tracking force to 3 grams(which is the factory setting for bypassing the tracking force adjuster), and using a scale to set your VTF, by moving the counterweight, will give better sound. This is because in the Rega RB300 arms, the spring that provides the tracking force, also causes a vibration in the tonearm. Bypassing the spring will give better sound. This has been tried and found true by many Rega owners for years.
Unless the RB 300 is different than the RB 900 there is no DIN into which you can plug a better/new cable. The RB 900 is hardwired. I would agree with the first post. Lauerman is the place to start. Unless of course you have the upgrade bug. I hear the Rockport turntable is very nice and even at $75,000 some people considered it a good deal!
There is a DIN available from Galen Carol Audio that must be soldered in place at the base of the arm post. It goes on all rega arms, but you have to cut and solder. DIN is made by Cardas. Will fit your RB300 as well as Nrchy's RB900. Repeat: you have to cut your arm cable, and solder the Cardas DIN on.
I agree with everbody's input above. Definetly the stock tonearm wiring could use improvement. Don't know is I'd invest close to $300 on the (tonearm wiring) upgrade, but between $100-$200 sounds resonable and your T/T will sound WAY better.

Thanks for all the input. My concern about cutting the arm cable to solder the Cardas DIN connection is that the internal wiring in the arm presumably stays in place. If they used substandard cable, I doubt the internal wire is great either. Does anyone have contact information for Lauerman and Galen Carol Audio. I wouldn't mind chasing down those leads.

One option I would consider at this point is to upgrade the arm cable with the intent of upgrading to a better table down the road and keeping the arm since I have seen it coupled with better quality tables from other manufacturers. Any comments on the relative merits of the RB300 arm vs. other sub-$1000 arms?
The RB300 is a very good arm. If you want to spend more, then have a look at the Origin Live website. They do wiring mods, structural mods, VTA adjusters, etc., to Rega arms, and even make their own arms, which is what I bought, the OL Silver 250. Galen Carol Audio has all their stuff. I got mine there, and was happy with the product and the service. Just type Galen Carol Audio into your search engine. I use Google, and he pops up right away.