4x Mini Alpeh grounding questions

[HIPCHECK]

I have a very overbuilt Mini Aleph that I am wondering what to do with it next. It is has a 4x15 400VA Antek transformer, 2x PSU PCB. The heatsinks do not worm up much over ambient. Basically I have tons of room to grow with the current chassis. I have the options of making this chassis a higher power Aleph amp?

Another option is to make this amp a multi channel Mini Aleph. I would only have to drill/tap 4 more holes for the additional mosfets. I could stack the second set of amps PCB's on top of the current amps and run extension wires to the new mosfets.

So here is the question? What grounding scheme should I use when I run 4 amps from 1 toroid with 2 amps per PSU PCB?

Here are pics of the amp in question:
http://www.diyaudio.com/forums/attachments/pass-labs/291408d1342192694-mini-004.jpg
http://www.diyaudio.com/forums/attachments/pass-labs/291407d1342192694-mini-003.jpg
http://www.diyaudio.com/forums/attachments/pass-labs/291406d1342192694-mini-002.jpg
http://www.diyaudio.com/forums/attachments/pass-labs/291405d1342192694-mini-001.jpg

 

[Zen Mod]

same as with 2 channels amp

 

[acamilicko]

What a clean and compact build, very nice job!

However, it seems to me that fets are attached to somehow pretty thin part of the heatsinks.. Think that leading the heat to the cooling area ain't gonna be so fast.

 

[Bengali]

same as with 2 channels amp

for star grounding without use of the PCB, what gain is there to use
thicker copper piece of metal(1/8") thick vs. just a bare copper pcb?
Is current here in mini Aleph not large enough to make an difference?

very nice work HIPCHECK!