need a few watts of class A

[Upupa Epops]

Use TPA 6120A in bridge mode. Although this circuit is not working in class A, give you much more lower distortion than some Zen.

[mertol]

I will certanly sound dump but I got to ask what is TPA 6120 A ?

[Upupa Epops]

It is new headphone " superamp ", made by Texas Instruments, with high current capability, which give output power 1-2 W.

[Jennice]

At these relatively low voltage levels (for the supply), losses in Vbe, resistors, etc will be significant. Remember, that for most designs, output voltage vill be somewhat lower than the supply voltage for the gain/driver stage.
To optimize this, my bet would be to use a chip amp, despite it not being class A, or to use a rail-to-rail output op-amp for the gain stage, and let it drive a Vbias and output stage.
At these levels, there may not be a need for a "real" output stage - a driver stage with TO-220 transistors should be enough as output.

Jennice

[PMA]

Properly designed output stage based on "diamond buffer" structure and biased to class A will swing close to supply rails.

[peranders]

Originally posted by mertol
I will certanly sound dump but I got to ask what is TPA 6120 A ?

It's an extremely good current feedback amp which Texas thinks is good for driving headphones

http://www.diyaudio.com/forums/showt...138#post486138

You could also make an amp similar the QRV-06 but with hole mounted parts like in the QRV-03 . Both my designs have "high-end" diamond buffers.

SonnyA has made a simliar power amp also http://mirand.dk