Looking for a SPDIF cable from Adiogon

Greetings! I have been using a Kimber DV30 digital cable for a few years and now looking for a definite upgrade. The cable connects my miniDSP SHD DIRAC (love this unit!) to my Gustard X20 DAC (modified by Ric Shultz). The DAC is connected to my Primaluna Dialogue HP Integrated (AWESOME!) via Avanti cables, then to my Martin Logan Summit X speakers via Clear Day cables (double shotgun). I’m very happy with the equipment, but thinking a system of this much investment might need a better digital cable. Am I wrong?

Currently, on Audigon are these cables that I’m considering:
  • Black Cat Digit (not Mk 2) $475
  • Kimber Kable AGDL $399
  • Kimber Kable D60 $260
  • Nordost Silver Shadow BNC/RCA $299
  • Audience AU24 $364
  • Cardas Audio Lightning $300

I can also order an Avanti for $180.

I’m totally new to this and have only had the DV30 in my system for about three years. Any advice or thoughts to help me decide will be greatly appreciated!

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I have recently tested the Kimber DV30 (your existing cable) in both stock RCA terminations, Pasternack 75 ohm RCA, and DH Labs RCA-750 termiantions.  I have come to the conclusion that it's an okay cable, but really not that good.  It does appear to have good resolution, but it comes across a little bright and messy and artifical.  The poor man's Beldon 1694A from Blue Jean Cable still sounds better than the Kimber DV30.

A digitial cable can influence the sound of your system just as much as other things, such as interconnects, power cable, etc.  Several of your possible choices are all silver or silver-plated items.  The pure silver items can be very clean and clear, but they can also push too hard on the attack and resolution.  It depends on how warm your system is and the type of sound you want.  Another suggestion for more neutral digital cables are the Purist Audio Design.
Thank you for your comments.  I guess I just don't know what sound I'm missing, so not sure what I'm looking for.  Would love to try a few cables so I better understand the sound differences.  That's why I am looking at used because if I don't hear a difference then I haven't dumped $800 for nothing.  Guess I'm okay dumping up to $400 though, as strange as that sounds.

I hear what you are saying about silver cables.  That's a concern I have too. 
I'd recommend getting this $40 Apogee Wyde Eye digital cable from Audiogon that you can at least use as a good benchmark for comparison if nothing else.  I've used it for years and prefer it to my Stereovox (aka Black Cat) XV2, which sounds thin and hyper detailed by comparison, and John Atkinson from Stereophile also used it as his reference for a while.  It's a very solid and natural-sounding digital cable, so if you find another cable that significantly outperforms it in your system and for your ears you know you've probably got something.  (Just make sure to follow the directional arrows because it directionality makes a big difference with this cable).  And who knows, a $40 cable may end up working for you!  Just FYI, I've been told that you should always get a digital cable with balanced connectors and use a BNC-to-RCA adapter if necessary -- something about not being able to make an optimal connection between a digital cable and an RCA plug.  Best of luck in your search. 
Out of your list I have only had and used one, the Nordost Silver Shadow.

This was a HUGE improvement over my old Monster Cable spdif but no real surprise there.

An even bigger upgrade was to a Nordost Heimdall 2 but now you are really up there in price.

What I think you could expect from the Silver Shadow though.

Much more detail, less grain, very fast and taut in the treble and mids, possibly a little lean in the bass. If your system is already lean probably not a good idea but if you are on the warmer side it could really pan out well.
I've been reading a lot about the Black Cat Digit 75 cable and it sounds like a very nice cable.  Again, I can't try them out because that is just too expensive and then I have a lot of cables not being used.  I purchased the Primaluna because I wanted the tube sound, especially in the mid-range because I listen to mostly jazz and especially female jazz.  My speaker cables are silver, so I'm thinking I should stick with a copper cable and not silver.  The Black Cat is copper.  

I have the Kimber DV30 so I have a benchmark.  The Black Cat sounds like it will be so much more than the Kimber.  I guess I'll never know until I listen to it.  Hmmm....
I had the opportunity to purchase a new Kimber D-60 in RCA at a reduced price.  Just installed it and OMG what a difference.  It's like a veil was lifted and the clarity and sound quality is amazing.  I was reluctant to make this purchase because of some of the comments stating there is no difference in digital cables, but man am I glad I did!  Beautiful sound!  The DV-30 is going up for sale!