Aelius II

About the Aelius II

The Ypsilon Aelius II is a hybrid monoblock power amplifier using only two gain stages with no overall feedback, designed to provide high power with exceptional transparency and musical involvement. The first gain stage is a single-ended class A valve input stage, transformer-coupled directly to a push-pull MOSFET output stage, avoiding additional gain stages and preserving signal purity. It is rated at 200W RMS into 8 ohms and 350W RMS into 4 ohms, with wide-bandwidth transformers defining a frequency response of approximately 11 Hz–75 kHz (‑3 dB) and contributing to the amplifier’s clarity and control. The Aelius II offers balanced inputs (some distributors list both balanced XLR and single-ended RCA), using an input transformer to improve common-mode rejection, support longer interconnects, and maintain a very short, clean signal path. The symmetrical output stage employs N-channel MOSFET devices in the same-polarity topology, and the balanced output connectors carry the audio signal in opposite phase for true balanced operation. The power supply uses high-current inductors and valve rectification for the input stage to provide smooth, low-noise filtering. Each monoblock weighs about 45 kg and measures roughly 425 x 425 x 230 mm (W x D x H), reflecting very robust construction and allowing the amplifier to deliver high power with finesse, transparency, and strong loudspeaker control.