2nd systems- who’s got one?

I already have 3 systems and am 75% of the way to setting up my new 4th system.

my 31year old son finally moved out so now it's just the wife and I, so she gets an office and a sewing room and I get a 4th system headphone/near field room. My new room is 10' X 10' with 8' ceilings.

I think the biggest mistake I made in my audiophile journey is trying to build second system 

right now I have two separate systems  home theater only systems in living  and my dedicated two channel in garage 

Funny I just saw that Dylan show and then listened again...on jbl go3 sounded great.   Several systems...main, kitchen, bedroom,treadmill,office1,office2...

Agree with others here the second system is often an older first system, in my case a Naim Unitilite and Audio Physic Yarra 2's. 

2nd system McIntosh MX122, Sonus Faber, Anthem

3rd system Anthem AVM60, B&W, Rotel

4th system Naim

Music in 8 Rooms through Sonos/Roon.