Best interconnects used for around $500 +?

I have had excellent results with ClearDay single ended interconnects. These are all silvers, but are very neutral and musical to say the least. Besides Paul from ClearDay will send you one to test in your system, without any credit card. Just reach out to him and let him know what you would like to audition. Good Luck.

Agree with the Clear Day IC's. I own several pairs and they embarrass many, more expensive cables. They'll bring out the best of you CJ gear that's for sure. Very open revealing cables. Kimber KCAG is a very nice cable and you can pick them up used around $500, but I'd go with the Clear Days and either save the difference or pick up a couple pairs. If you can find a used pair of WyWires Silvers that's a nice step up from the Clear Day Cables, but they don't come up for sale used often. Good luck.

Try the usedcable.com lending library. I did years ago and have settled it was a great help in finding the right cable for my system.

I have been very pleased with Herron Audio cables.  I haven't had any reason to change.  That said, I have not heard a very wide variety of cables.

What interconnects are you using currently and what specifically are you looking to improve upon?

I currently have the Audience au24se interconnects and they are very good.  I've demoed others under 1000 and these were my favorites.  They are very fast, dynamic and neutral.  I have tubes in my system and they were my personal favorites at the 1000 point.  I did demo the Wywires silvers and slightly preferred the audience au24se in my system although in another system the Wywires might be better.  For around 500 the SE's are a great value. 

From my experience, I would highly recommend you try out either used Tara labs air 1's, or Zu audio mission (new) or even better Zu audio event (if you can find used) which should all be within your budget and provide an amazing value for money. I have yet to hear IC in that price range that even come close to these. But, there are so many different cables out there that I never heard... :-)

Mrotino describes the Au24se well. I use them myself pretty much throughout my system. The only thing I'd add is that you could consider also trying Audience's Ohno ICs, which come surprisingly close to the Au24 but at a fraction of the price. 

Purist Audio Design Musaeus :-)

Forget about the AU24SE.  Should be considered the Audience SX series for ultimate musical sound just for a little more money but well worth it!  I had them both in my system and the AU24SE is not even close! 

The Audience SX delivers performance that other cable manufacturers charge 3-4X the price. 

Check out the Cerious Technology cable thread.

I've recently replaced my FMS Nexus IC's with Von Gaylord 7000 ICs. If you can find a used pair of the FMS Nexus cables, you'll be more than happy. They were really expensive when new, but can be picked up within your price range used. 

If you are on a budget and know how to use a soldering iron then DIY is the way to go. Use AWG 16 gauge fine silver wire dead soft (Riogrande) and untreated cotton sleeve as dielectric. Go for best termination plugs pure silver (WBT or KLE). Kimber's top of the line Select interconnects don't even come close! 

Purist most musical.

Several Years ago when I had a CJ CV12 preamp I used MAC silver cables with good results. Currently I too use Clear Day ICs with my Odyssey system including a tubed preamp. Very nice combo. But I did test drive the Ohno and Purist Vestas. WhileI thought the Ohnos were thin sounding the Vestas were beautiful, musical. They run around $300. I had two sets testing between dac-pre and Pre-amp. Ultimately I went with the Clear Day for additional detail but if you are looking at musicality vs detail with less musicality the Purist were really something. I can only imagine as you go up the line. I tested both through the cable company. May went to test two pair of each to put get the full picture. Regards.

As someone who goes into almost every cable A/B test skeptical that I will hear any differences, I usually end up convinced that I hear some differences only to be left wondering if it matters. Recently I borrowed the Audience  au24se XLRs and couldn't believe how veiled my system became. I looked at the terminals and the connections just to be sure there were no issues there and all seemed well. Left-Right was identical. Extremely disappointing compared to my Audioquest Columbia 2m balanced ICs.

I know you're asking about SEs and not XLRs, but I still believe this is a worthwhile data point whether it be related to build quality, design philosophy, etc. Disappointing is disappointing. When I compare expensive ICs I don't expect to hear that.

DNM HFTN IC cables run about $500.00 new and to my ears are very hard to beat at 4x their cost.

KLE Innovations gZero range, if you can find them.

Very hard to find and they go quickly

The gZero6 and up are excellent.

Regards