I sore this is going to come down to opinion but looking for some opinions before spending several thousand! 
I have a 6 zone Linc system ( only 5 zones connected ).   It’s in a rental home I own so it’s not possible for me to trouble shoot ( I’m on the other side of the world ).  I’ve had problems with the htd in the past with noise coming though the speakers and HTD were good enough to replace the remote thing!   But it’s acting up again.  

To be honest, I don’t need 5 discrete zones. I could get by with pairing the master bath and master bedroom. As well as pairing my kitchen and Gabe’s room.  Add on the patio and I really only need three. 
 

I also think the 6 source inputs is overkill   To be honest we never really ever listened to different music in different areas. But being able to select from a couple of inputs would be beneficial  

I was thinking to buy 3 Sonos amps and be done with it. Then I stumbled on to Sonos port and though I could have done money and drive my multi channel amp with 3 ports. 
 

I do have some questions if anyone is able to help me understand the differences and Pros / cons. 
 

Port.  
Would need three ports to create 3 discrete zones. Yes?  
I believe that the port has a line in if I want to connect a different source.  I’m thinking I’d like to have a BT option for anyone who visits that would like to play music from their device without logging on to my network. ( presuming I’d use a BT adapter connected to the port ).  But. If I have 3 ports im Assuming that I would only be able to select an external source on a single port at a time.  Yes? 
If I have that right are there any work arounds? 
pro   Cheaper to buy 3 pros than 3 amps  

con I’d be using my 12 year old HTD amp and who knows how much longer that will last ( that’s if its not already the problem with my current setup ) 

AMP  

again assuming I’ll need three separate amps to create 3 zones  

Also assuming I’m going to have the same problem with an external line in….if the amp even has a line in 

Pro   Not using my older htd MC amp that might give out  

con   Amp prices seem to be running 350 usd more than a port   So it’s an extra 11 or 1200 after tax  

anyway  I’m planning on taking advantage of any BF sales in a month so appreciate any thoughts 

thanks in advance  

Mac