Where to improve phono chain?

You may want to consider getting a speed control. They usually make a big difference.

or find a local dealer and take your rig in and see what else is out there and really understand what's good and what you don't like.

What about a really good IC between the phono preamp and your preamp? That will help bring out the most of what you have. Problem is - a good cable can cost as much as a good phono preamp, so it could be a difficult choice of which to get first.

Honestly, you must look at your cables like a component. If you want the best sound, you have to keep it in your mind. LIke a component, there are price points you need to be at in order to get the best sound for the money. I'd try to borrow some AQ cables to see if that does the trick. Cardas would mellow things a bit. Personally I like to get neutral cables and then buy the correct components for my ear. I have never heard a system sound great when using cables to try and 'tune' it in. JMHO

You don't mention if your TT sits on a decent foundation. An HRS, SRA, or Symposium platform will make a world of difference to you analog. Far more than anything mentioned here. You don't know what you already own until good mechanical isolation is achieved and this would include all your other components.