I can only give you my feedback regarding Simaudio Moon and Ayre. I have not used Classe or Pass in my system. I have also used Arcam, Rotel, and Parasound amps.
I use a Monarchy tube DAC with DIP as a front end. Speakers are Green Mountain GMA. All interconnects are DIY magnet wire as are the speaker cables. I listen to a pretty wide variety of music with a lot of jazz, classical and acoustic guitar, piano.
I tried the Simaudio I.5 and now have an Ayre AX7e (see my review under "reviews"). For me, there was no comparison. I tried the I.5 with multiple cables and interconnects and simply could not tolerate the sound. It was precise to the point of being analytical and cold. Instrument timbre seemed coarse and harsh with a high degree of listening fatique. The Ayre by comparison has been the best integrated amp I have heard to date and is in my system to stay. Musical timbre is faithfully produced, instrument separation and placement is amazing without sounding analytic. On top of that, Ayre has some of the best support out there.
I went through 5 amps in two years and wouldn't even think about changing this one.
I use a Monarchy tube DAC with DIP as a front end. Speakers are Green Mountain GMA. All interconnects are DIY magnet wire as are the speaker cables. I listen to a pretty wide variety of music with a lot of jazz, classical and acoustic guitar, piano.
I tried the Simaudio I.5 and now have an Ayre AX7e (see my review under "reviews"). For me, there was no comparison. I tried the I.5 with multiple cables and interconnects and simply could not tolerate the sound. It was precise to the point of being analytical and cold. Instrument timbre seemed coarse and harsh with a high degree of listening fatique. The Ayre by comparison has been the best integrated amp I have heard to date and is in my system to stay. Musical timbre is faithfully produced, instrument separation and placement is amazing without sounding analytic. On top of that, Ayre has some of the best support out there.
I went through 5 amps in two years and wouldn't even think about changing this one.