  One of the main issues that real energy converters present, when they produce
effective work, is the inevitable entropy production. Within the context of
Non-equilibrium Thermodynamics, entropy production tends to energetically
degrade man-made or living systems. On the other hand, it is also not useful to
think about designing an energy converter that works in the so-called minimum
entropy production regime since the effective power output and efficiency are
zero. In this manuscript, we establish some \textit{Energy Conversion Theorems}
similar to Prigogine's one with constrained forces, their purpose is to reveal
trade-offs between design and the so-called operation modes for
$\left(2\times2\right)$--linear isothermal energy converters. The objective
functions that give rise to those thermodynamic constraints show stability. A
two--meshes electric circuit was built as an example to demonstrate the
Theorems' validity. Likewise, we reveal a type of energetic hierarchy for power
output, efficiency and dissipation function when the circuit is tuned to any of
the operating regimes studied here: maximum power output ($MPO$), maximum
efficient power ($MP\eta$), maximum omega function ($M\Omega$), maximum
ecological function ($MEF$), maximum efficiency ($M\eta$) and minimum
dissipation function ($mdf$).
