It's also worth to try out another Wifi router.
Maybe you can borrow one from a friend / neighbour. Please use a NON Apple router. Apple is known to ensure that it only plays fine with other Apple stuff and that older Apple stuff will be slowed down until you voluntarily upgrade to the newest things.

TWG wrote:

Apple is known to ensure that it only plays fine with other Apple stuff and that older Apple stuff will be slowed down until you voluntarily upgrade to the newest things.

With due respect, what basis do you have for that statement?

davelarue wrote:

I connected my Playmaker to the ethernet port of a new airport extreme. I still get dropouts, however a bit fewer than before when i used wifi only.

Also the PlayMaker is 2,4ghz only which is almost impossible to be made perfect. A recent AppleTV or Airport express operates at 2,4 and 5,0ghz so the chances of wifi issues for most domestic situations are minimised. If the PM is cabled directly are you confident that it's operating on wired connection not still wireless?

davidr wrote:

Also the PlayMaker is 2,4ghz only which is almost impossible to be made perfect. A recent AppleTV or Airport express operates at 2,4 and 5,0ghz so the chances of wifi issues for most domestic situations are minimised. If the PM is cabled directly are you confident that it's operating on wired connection not still wireless?

How do i check if it is working on wired or wireless? 

Open AirPort utility, check if you see it as a client on wireless.

Only airport extreme is visible on airport utility...

Beobuddy wrote:

What are you using for playing music? Phone, tablet or pc?

I haven't had good experiences with my playmaker (mk1, hard wired).

Only when the music was stored on my phone or tablet it played without dropouts.

I had a lot of problems initially with my PM. Then I noticed that it played fine with streaming from my phone or my tablet (iOS devices) but had significant dropout issues playing from my PC, using iTunes on Windows 7. Turns out there was a network/router monitoring application on my PC that, when it wanted to poll the status of the router, basically stomped on all other network traffic, it seized a high priority and everything else stopped until it was done. I removed it from the startup menu (I only run it if needed, then exit the program) and it solved the problem with dropouts from the PC.

So, be aware dropouts may not be due to the router or wired/wireless connection, but may be due to other things going on with the PC itself.

davelarue wrote:

Only airport extreme is visible on airport utility...

Click on it and it should pop up a display of the wireless clients.

I suggested that more as a precaution check.

Also Jeff brings a good point, what is the source? Is it also wireless, what is it doing?

I get similar amount of dropouts when using the phone. However, when i play songs which are stored, then the dropouts are less frequent. The problem could mainly be when i am streaming. 

BUT, this shouldn't matter. My 2009 airport express didn't have any issues with these scenarios, so why should the PL?

davidr wrote:

Click on it and it should pop up a display of the wireless clients.

I suggested that more as a precaution check.

I don't see the PL in the pop up. So, i should assume that it is running on wired connection?

davidr wrote:

TWG wrote:

Apple is known to ensure that it only plays fine with other Apple stuff and that older Apple stuff will be slowed down until you voluntarily upgrade to the newest things.

With due respect, what basis do you have for that statement?

for example:
https://www.macrumors.com/2015/12/29/ios9-iphone-4s-lawsuit/

https://www.scribd.com/document/294247024/IOS-9-Slows-iPhone-4S-Complaint

http://globalnews.ca/news/2926170/is-apple-guilty-of-using-planned-obsolescence-to-force-iphone-users-into-upgrading/

My personal experience is the same beginning with the first iPhone and iPad.

Router problems obtained in many installations from my friends.