Turntable/Arm/Cartridge Upgrade

I'd like to get some feedback from people on an upgrade path. I currently have a older (10 yrs or so) Rega Planar 3 with some minor mods, the RB-300 arm and a Sumiko Blue Point Special. I'm running it into a Classe 6 MKII Pre with a pair of Classe Dr-8's and Vandersteen 3's. I'm thinking about upgrading the whole analog setup but I'm wondering how much money I'm going to have to spend to make it really worth it. Any Ideas and suggestions would be greatly appreciated.
I've had exactly your analogue setup and upgraded to Michell Gyro SE. I kept RB300 and later-on modded with Incognito kit and Clearaudio heavy counterweight. There were a few cartridges and Lyra Helikon is current. Before I've acquired Benz M.09 for half of price and was also very pleased. Now I have Benz M.09 as a backup or I might sell it as well if things won't go well.

So my setup is now(new prices)

Michell Gyro Se -- $1200(no arm)
RB300 Incognito mods + Clearaudio heavy counterweight --$350
Lyra Helikon(acquired from overseas) -- $1200
Walker Audio disks only(as a part from valid points) -- $60

This setup literally drives me so crazy that whenever I try to listen to my digital setup, I get fatigue an few minutes and switch back to vinyl. Besides above list I would certainly suggest a dedicated phono preamp instead of built-in. In my case I have ARC PH3 that I call "Botomless beauty" in the sence of that there is no limit to its bottom.

If you will deside to stay with your Classe preamp, you should go for higher output cartridges such as Dynavector 20XH, Benz Glider H2... Sumiko BPS is great but there is no 3D imaging from that cartridge due to the limit in bottom-end resolution. From the simple principals of electrical engineering I can tall that the larger coil has larger inductance and so larger voltage is being dropped on the bottom freequencies. So the lower output carts have much better 3D and bass.
It may be more costly than you were planning, but, The Well Tempered Reference with a Grado Reference is a reliable and extremely musical combination. You may find the table and arm used, and affordably, and should enjoy the high output of the Grado. The key to this combination is proper setting of the damping (along with the usual adjustments). Begin with the paddle only 1/2 submerged in the fluid and make fine adjustments from there. You will know when you get it right. I have heard this combination hold it's own extremely well compared to far more expensive analog front-ends.