KAS audio often auction pairs of their Maestro cables.
If you could win a pair these are exceptional value for the money.
I have two pairs which compare favourably to Kimber Select KS-1030.
Other than that I would recommend used Kimber.
Acoustic Zen silver ref. I have the pass X250 and a pass d-1 dac with the AZ and they are by far the most open and detailed cables I have used so far. I do have a 1 meter set on agon now below your price range I move my set up and needed a longer pair. If interested let me know.
Given the quality of the preamp and power amp you chose, it would be a mistake to "ease in" too easily, when for a few hundred dollars more now you can avoid having to upgrade at all. On Audiogon you can get a pair of superb balanced cables used for $750-$900 which cost around $2000 or even more just last year. The two obvious (to me anyway) suggestions are HMS Gran Finale (the balanced IC version is probably the best of all of HMS' cables) and Purist Proteus. I've used both between a Pass X1 and Aleph 2, and thought they were both excellent, with the HMS especially warm and still detailed--a perfect match. Good luck.
You might want to give Discovery Essence a try. Discovery has always used Pass equipment at CES and the combo sounds and works very well together.
on my system Audience AU24 are great ICs with superb detail and a forward image with a great bass that is not heavy but instead involving and natural with nice skin effects on drums etc. Also their detail is not bright or etched in the slightest. A really great IC for less than $500 XLR.
The AZ Sil Ref MKI or MKII are the way to go, I own the X-1 and X-250 right now and use the AZ cables, for the used prices, nothing beats them.
Thanks for the suggestions, guys. Choices, choices....
Unrelated to the Discovery Cable post...I've had the X1 and and X600 and used the Discover Plus 4. They have been some of the best cable I've ever used (assuming your equipment is up for it). I think yours definately is. I haven't heard the Essence, but I've heard about it. Go for that!
Kimber Hero's will fit the bill. I never got the feeling Nelson Pass was much of a fancy cable fan. His intentions seem to focus on the engineering to such degree as to make their use an indulgence. But hey, I've heard beneficial differences just by rearranging my existing power cords. It sounds like you're already planning a little gift for your new pre/power combo. Rest easy. The Pass gear is good enough to make a big splurge unnecessary. Go crazy on a balanced front end instead.
Since owning the X2.5 and X150.5 I haven't cable swapped, I have only used Audience Au24 and have no plans to try others at this time; take that for whatever it is worth. In a past setup I compared the Acoustic Zen Silver Ref II and chose the Au24, again, take this for whatever it's worth. You may also want to consider the IC's from Pure Note.
The Pass gear is very critical of cables (like my Krell). I suggest you spend more dollars now instead of buying upgraded cables later. My suggestion is the Pure Note Cerulean. These are phenomenal cables for the money and you won't have to upgrade. Do a search and you will find many positive posts on these.http://www.purenote.com
Acoustic Zen Matrix II between X250 & X preamp & AZ Silver Ref II from CDP to preamp, all XLR, was the best combo I found with my rig, tried others that were more $$$$.
I've tried many IC's with my Pass X-250 to Sim P-5 connection. I ended up sticking with Audience AU-24 XLR's. Great synergy with the X-250. They're the best I've used (including Cardas Golden Reference, Neutral Reference, Acoustic Zen Matrix and Silver Reference, Ridge Street POIEMA (a close runner up) and the Pure Note Epsilon Reference V4 (another Excellent contender).
Virtual Dynamics is a great match to the Pass gear, especially between the X1 and X250.