So, where the thought process is begins with the power cord. The power cord really always needs to come into the back of the component. We could put the power entry on one corner, then we could put the phono inputs on the other back corner. It would be nice to have about a foot between them, so now we have a 12" wide phono preamp. We would want to pile up the small signal tubes right next to the phono level inputs, then the higher signal tubes can be closer to the power transformer, then the output jacks, then the power supply regulator.
This landed us at a 12" wide by 8" deep panel. Ultimately, with a 12" deep BeePre or Stereomour, it makes a bit more sense to rotate the whole thing 90 degrees so you could put the Eros 2 on a shelf next to another 12" deep component. Given the 8" width and 12" depth, there's not enough room on the back panel (in our opinion at least) to have the input jacks and the power transformer, and the power entry module. That's a bit of a noisy region. Moving the input jacks up front keeps them well away from those noisy areas and makes the connections between the input jacks and the EF86s nice and short. It also provides the ideal place to mount step-up transformers, as they are physically about as far away as possible from the power transformer.