Pro Audio Design Forum

What kind of phones are you trying to crank?

Those 7506's are really efficient headphones. It doesn't take much to make those hurt the ears. My requirement for a headphone amp is that it must be able to drive a set of AKG 240M's loud enough to hear a mix while playing drums with earplugs in. (then cross fingers the click doesn't bleed )

Looks nice! Has a similar vibe to the small DBX units!

Nice build! I had my Dad make me a pair of walnut wooden end-caps for dBx extrusion like that years ago and I should use them. I had a 3BX that came to me rack-mount I wanted to convert.

I also use AKG K240Ms and I am certain I need more gain for those being higher impedance, 600Ohms.

I think you have a vintage pair of K240s. IIRC they're now around 50 Ohms. For those, you might turn the 1246 gain resistors around backwards to give you +6dB gain rather than -6 dB. The original K240s always did require a lot of drive voltage.

The 7506's are ear splitting at just a volt or two with a 63 Ohm 106dB/mW sensitivity.

It should be unity gain. I haven't had any lack of adequate drive with cosnumer level "-10" stuff.

You might try the +9 dB trick here: viewtopic.php?f=6&t=23&start=100