Looking for advice on my first rack. I put a lot of thought into it but I'm still very confused until I get hands on with this stuff, so I am seeking advice/opinions.

So far I own Maths, Monsoon and Beehive. I will be sequencing externally and can get drums externally but I did add the Expert Sleepers to the build for drums in a pinch and also the many other things it can do. I'll probably be using my polyend tracker for drums and sequencing via midivolts 4 channel cv/gate and clock output. I also have a few other things I could use if needed but I love my tracker and would be the preferred device.

My end goal is to have something to make spacey ambient stuff, and sounds and melodies I can sample for hiphop and electronic music production.

I have a B2600 I will be using with the rack for a while as I build up my collection.

I am getting my amp and mixer next. What modules should I be looking to get afterwards?

I would like to expand to a 6u build at some point.
ModularGrid Rack