Weakest Link? Your honest opinions.

Before I spend any more on audio equipment, I'd like some opinions on my current vinyl rig:

Nagaoka MP200 Cartridge (this I will be upgrading to a Zephyr as soon as possible)>

VPI Classic 1>

Blue Jeans BJC LC-1 RCA Cables>

Jolida JD9 Phono Stage>

Monster RCA Cables>

Marantz PM-68 Int Amp>

Canare 4S11 Star Quad Speaker Cable>

Kef Q55 Speakers (bi-wired)

Everything aside from the turntable/cartridge I've had for 5 to 6 years, and are my first foray into HiFi audio.

Just bought the Classic 1 recently, and I'm loving it so far, but I feel a better cartridge will really improve the sound. The Nagaoka was used previously on my Rega P1 (which I'm using in my office rig). I'm saving up to buy the Zephyr, but does anyone notice any other obvious faults in my system?

I feel like the Marantz and Kefs could be replaced at some point, but I wouldn't want to make a purchase unless I know it's going to make a significant improvement over what I already have.

Also, does anyone think some part of my rig might prevent the Zephyr from performing as well as it should?