Introduction
An output-transformerless (OTL) amplifier has to vex some audiophiles and engineers alike those who cling desperately to the notion that there is a single unerring "proper" way to design an audio amplifier. On the one hand there is the dictum that fewer parts are best for sound, and that must go double when it comes to eliminating a component as dominating as the output transformer. On the other hand is the notion that the output transformer is of absolute primacy akin to wheels on a car. Without it, there is nothing smoothing out the amplifier's impedance and making the mating of amp and speaker possible.
Conclusion
Early on in this review, I discussed my personal list of the very best amplifiers I've heard, reiterating the diversity of amplifier technology in the process. To get specific, I'd choose two solid-state amps (the Ayre MX-R and Luxman B-1000f monoblocks) and three tube amps (the Convergent Audio Technology JL2 Signature Mk 2 stereo amp, the Lamm ML3 monoblocks and the subject of this review). These represent a cross-section of amplifier technology: high-power solid state, high-power tubes, single-ended tubes and output transformerless. I didn't assemble this particular list in order to prove my egalitarianism; I simply collected the five amps I've heard and admired most. I could have expanded it to ten amps, but that would only cloud the issue by sending the message that "best" is a more elusive goal.
Keeping the notion of "best" in mind, let's say that I don't have the luxury of picking five amps. I have to choose just one -- the amp that will be the conduit through which all of my music, digital and analog, passes. Which will it be? Solid-state or tubes? Push-pull or single ended?
Give me OTL in the form of the MA-2 Mk 3.1s, and I'll live musically ever after.
Source & Complete Review: theaudiobeat