I have 8 Dell 5548p switches that, as of now, all use port-48 as a jumper back to our main 5548p switch using a CAT 5e patch cable.  I recently decided to "stack" them.  I bought the cables from Dell.  My question, if I stack them, do I need to power them all down, connect the cables then power up?  Will I lose any of my existing configurations (VLAN's, etc..)?  Is the correct way to do this to run 1 HDMI cable from HDMI Port 1 on the top switch back to the main switch (HDMI Port1) and stack the rest going down the rack HDMI Port 2/1, 2/1. 2/1, etc..