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This paper deals with a t h e o r e t i c a l c i r c u i t analysis of a single-ended push-pull audio amplifier. Linear tube characteristics and small signals are assumed. The problem of impedance matching is first discussed. The properties and the requirements of a s a t i s f a c t o r y d r i v e r s t a g e are analyzed, and an output stage using an impedance matching output transformer is discussed. The effects of the plate-to-ground capacitance of t h e d r i v e r stage on the frequency-gain characteristic and of the choice of the tube and circuit parameters are analyzed. The paper concludes with some experimental results indicative of the inherent properties of the amplifier. In a r e c e n t a r t i c l e by Peterson and Sinclair,l special c i r c u i t s have been suggested by which a high fidelity, low d i s t o r t i o n audio amplifier can be constructed without using output transformers or i n which the requimrnents of an output transformer can be greatly simplified, The present a r t i c l e will give a t h e o r e t i c a l analysis of the b a s i c c i r c u i t used by Peterson and Sinclair. It will be observed that many desirable characte r i s t i c s of t h i s a m p l i f i e r c i r c u i t can be deduced from this analysis.