Who said, that something exotic shall be expensive by default? You can got you 150 EUR worthy of exotic exploration with this new amp from Toroidy.pl. 2×2,5W stereo Single Ended vacuum tube amp (4xPCL86) with DT5 chassis and output toroidal class A transformers. Do You still think Single Ended amp is not possible with toroidal output ? These guys have patent on it..