Thoughts on wireless subwoofer.

Have you considered just running a set of cables from your speakers to the sub/subs?  Your speaker terminals allow for both spades and bananas so connection will be really simple.  Of course the sub/subs must allow for speaker level input.

Yes
As I said any physical connections either from speaker terminals or RCA gave an unacceptable ground loop hum.
However speaker level connection to subs from an Ayre a7xe is anything but simple I am afraid.
But thank you!

I can commiserate about trying to hook up a pair of speakers and subs on the A7xe. Those binding posts make adding 2 pairs of cables a bit of work, but, it can be done.
B 

Dear @uberwaltz: I have not experience with wireless subs. Now and due that your speker woofers crossover 300hz you need to use an external good quality crossover ( Bryston is an example or Pass. ) to relief the main speakers woofers from 80hz and down.
Using the speakers full range along the subs is a big mistake and not the way to go because the main target when using subs in a stereo music home audio system is to improve the IMD lowering it at much we can and when you make what I said you are achieving that critical target and then your system sound will improves in a huge way putting you nearer to the live event. You need two powered subs connected in true stereo fashion.

If the powered subwoofers comes with a good quality high pass filter then you don't need an external crossover that normally has better quality performance.

Either way you need to contact Mr. Jansen ( I think is the Ayre owner, maybe I'm wrong. ) and explain him the trouble you are experienced and see which are his advise. Maybe a new integrated amp because yours has at least 10 years was designed.

In the other side maybe the trouble could comes from a not very good subs design you have, I can't know for sure.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

Raul
Thank you
Unfortunately I have already ordered a Martin Logan Dynamo 700w sub.

But I do see your point exactly on cutting the lower freq to my main speakers as you would in a ht rig with small sat speakers say.
I can see how the combined low freq from both the mains and the sub may make it harder to integrate the sub seamlessly.

I did speak to Ayre before pursuing this and part of the problem is the way the ax7e is built as a fully balanced unit and it just doen not play nice with some subs depending on THEIR grounding design.

There has been a couple of important threads on this previously which Almarg was kind enough to make me aware of. If he had not and I had just connected a sub up using the speaker terminals as common practice would have you do so I could have actually seriously damaged the Ayre internally.

See this...
https://forum.audiogon.com/discussions/subwoofer-for-ayre-ax-7e

So I will try the wireless approach although it does mean I have full output at the tape loop output but I could likely find a unit to insert inbetween that that would turn it to a variable output. Only just thought of that and I am sure something must already exist for that function, to take a fixed rca output and give you the option to vary it. Google search time!

But thank you Raul.