I have built 3 headphone amps so far,
a small battery driven portable amp was my first project,
second was a 3ch, active ground M³
and my latest is a 3ch, active ground Beta22.
Each amp has its advantages, it's not only about sound quality.
The "best" amp?
That depends on the phones you are going to use .... it's a lot about synergy ... and also on the rest of your set up ... DAC, source, cables ....
I'm not into tube amps ... but I'm sure there are some set ups where tube amps might be the "best" solution, too.
If you are going to use a Beyerdynamic T1 or a Sennheiser HD800 as main headphone, I'm sure the Beta22 will be great.
