There is pure class A integrated amp called microZOTL 2 from LinearTubeAudio (https://www.lineartubeaudio.com/products/mz2mz2-s). It uses signal tubes only for sweetest sound I have heard recently. It has two inputs but it's only 1W/channel so you need very efficient speakers such as Teresonic http://teresonic.com/magus/. That combination can beat 20K+ systems with the sound quality.
