Ok, as to layout. working with a rectangular top plate we have the Xformer and choke at one end (you have to decide what is "front" a long or short side) now how about a power switch? AC connector and fuse if panel mounted. a good place for the switch is the near back corner next to the Xformer. Somplace easy to get to that you so you don't burn yourself on the rectifer. it can be up front but we want to keep the AC as far from our circut as we can. Next rectifer and big cap. We want the rectifer out were we can see it and bask in it's glow, so how about in front of the xformer, with the cap next/behind it, close by but not so close that it will cook. The cap is our B+ point and master ground point so don't hide it. Next input/output jacks and controls. Using a long side as front I would run my RCA jacks in 1 or 2 rows starting near the back corner away from the Xformer and my Vol control at front right. A slector switch could go next to it or in back near the jacks. If you are planing on more than 1 input, go ahead put the jacks in now and plan room for the switch but wait untill the pre is working well before adding them. Mount 1 or 2 tube sockets behind the vol control maybe 2" back, leave room between them and the jacks we have 2 large output cap and CCS to fit in there plus more tube sockets down the line...John