Need advice on power cords for my Ayre system

Theo is correct. Ayre recommends the Cardas power cables on their equipment. Because of the level of internal power filtering, don't expect any huge changes to your sound. Ayre equipment is is not really effected by power filtering or cables as a lot of the equipment out there is.

I own a CX-7 and a K-3x preamp. Ayre gear, the CX-7 in particular, definitely is effected by power cords. I've used the VH Audio AirSine, TG Audio SLVR, Audience PowerChord, Custom Power Cords 11 and the AudioParts Audio One Reference in this system. I've also tried Cardas, Virtual Dynamics and Elrod cords (but not their Signature or Statement). The AirSine is the best of this group but also the most expensive. I would try a VH Audio Flavor 4 on your V-5xe and an AirSine on the CX-7. I think the K-5xe will be the least effected of your Ayre components but you'll have to experiment. The VH Audio Flavor 2 would probably be a good choice for your tuner and headphone amp but the Flavor 4 or the Audio One Reference would work there too. Contact Chris VenHaus (VH Audio) he'll give you good advice and has a return policy if you're not happy. Stu at AudioParts offers a return period too.
An in-between choice, cheaper than an a VH Audio AirSine but more expensive than the Flavor or Audio One cords would be the TG Audio SLVR or 688 (avoid the earlier HSA).

Art Dudley of Stereophile in the latest issue says very nice thing of Cardas Golden Reference when used with the Ayre integrated amp as well as his other equipment.

My view would be you should definitely invest in good power cables for your equipment. You already use top notch interconnects & speaker cables with highly rated equipment and I am sure the benefits of good power cords will come through clearly. In my experience, even equipment which has extensive filtering in their power supplies benefits from improvements from power conditioning & cables.
I would also concurr with comments on VH Audio Flavour 4 power cables. An excellent power cable for very little money (especially if you DIY) which compares very favourably with cables up to the $900 - $1000 mark.
Trust this helps.

I used the Cardas Golden ref in my system as well. But the mid freg are very poor. Because it cuts a freq. part in the mids. A Purist is superior in every part where you have to judge a cable. It can go a lot deeper in the low, the mids are much more open en the high's are also more open en sweet as well. A Valhalla is superior better in speed and resolution than a Cardas is. You are comparing a Ferrari with a Ford.