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).
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).