I run the A21 with a pair of Wilson Sophia 2 speakers and I have never for a moment found myself wishing for more. The raw power of the amp complements the dynamic punch of the loudspeakers very well, with a full bottom end, palpable mid-band, and crystal highs. Years ago when I bought the Parasound unit I was listening to other models at local hifi shops, like Rotel, Yamaha, Bryston (oh, how I loved the 4B SS2), and some pricey equipment from Balanced Audio Technology (...sweet stuff...). I really appreciate how effortlessly the A21 performs, letting you pick out singular instruments in detail amidst a layered, complex passage of a recording. Working with some other amplifiers I've also learned to respect the A21's apparent immunity to hum introduced by AC line noise. The transformers in my other home-theater amp sing like birds when certain household devices are running... You may buy one and later fall in love with something else, but you will still feel like you got more than you paid for!