headphone preamps, suddenly no bass?

[The Dong]

Michael Zacherl wrote:
> maybe someone has an idea what's probably wrong with my SM Pro Audio 
> headphone amp:

If one channel is somehow out of phase, that would cut a lot of the 
centre sound.

Unless you have a tool to check caps in-circuit, or can see a damaged 
one, the 'let's blame the caps' angle could be futile ;) but if the 
circuit has equalisation...

Only logical way to trace is to feed the amp with a low tone that is 
being chogged, then scope through the audio signal bits of the circuit 
until you see a problem then narrow it down. Chav. Unless you are still 
covered..