Are Denon Audessy and Yamaha YPAO (AVR tuning mics) interchangeable ?

Ive got a Yamaha AVR, but have lost the YPOA tuning mic, ive got a spare Denon Audessy, and wondered wether i could use the Denon unit to tune the Yamaha AVR.

Similarly ive lost the tuning mic for a Velodyne subwoofer and wondered wether the Denon Audessy would work to tune the subwoofer ?

Probably not. I bet it would work, just not well. These tiny mics are not very accurate so there is a correction built into the receiver for them. my guess is the correction is not the same for Audyssey, Velodyne and Yamaha. It wouldn't hurt to try it though.

???
Unless he has both microphones and does and A/B comparison, there is no way to know how far off it is. So actually... it would hurt to try. Because you know someone is going to do it, it will give results and a tuning, then they will think it worked fine and leave it. Completely oblivious to how bad it might have adjusted things.

It is bad enough that these things are only so-so accurate to begin with. I never trust them, I always manually set everything and adjust using my own RTA.
A/B comparison always shows the self-calibrating setup is usually off by a little. Usually not a deal breaker on most systems but depending on the receiver and room, can get some quirky results sometimes.
I often wonder how many systems are out there that someone has ran the self-calibration, it completely screwed it up, and it was left like that (by DIY & professionals alike). Because they lack the basic understanding or knowledge to know better and test equipment to verify.
I mean look how many people use an RTA app on their phone (no external equipment) and adjust systems with it. Not taking about an SPL meter app and just adjusting sound levels, they actually try to 'tune' the EQ with the mic built into their phone.

I meant it probably wouldn't damage the equipment if he tried a different mic if they both use the same connector. He can see if he likes the results or not.

I agree without an RTA, TEF, MLS, FFT, etc. there would be no way of knowing how it did for accuracy. Levels and distance it would probably get correct as they are relative, it is the EQ you would have no idea how well it did, only if you like the sound or not. On most receivers you can turn on/off the EQ. While it might not be accurate he can listen and see if it made an improvement to his liking. In this situation it wouldn't be about accuracy.

Being a calibrator I like to adjust these myself as well. I use a TEF system which has an RTA and other measurement types as part of it. I use different types of measurements depending on what I am measuring. For the average home owner which is unlikely to pay someone like me to do calibration it is simply a try it and see if they like it scenario. With a generator and SPL app they could at least verify the basics were correct. I wouldn't recommend anyone use an RTA or other frequency type measurement with a phone or tablet's internal mic to manually adjust EQ.

Bob you are using the new Studio Six Digital setup now correct? Or was it still Gold Line's TEF25?

Still the TEF25, I played with the Studio 6 and there are certain things I like better about the TEF especially for dealing with reflections. Certain things I like better about the Studio 6 especially the integration but not enough new things to warrant the change and tough to justify. Video cal stuff might be our next upgrade the PR-650 is getting old and expensive every time we send it to be re-calibrated. I talked to Gerry on it and he told me he approached Gold line a while ago to put together a package for the HAA and integrate with HAA software but they weren't willing to do it:-(