How do you know when tubes in the phono section of the integrated amp go bad..

Hi -

Those would be 12AX7 tubes.  At the worst, treat it like any other input tube which would be at least 5000 hours.  

No expert here.

Rich 

Yeah. I meant, of course, how to notice a failure if I can't see or hear it without removing them and putting them in the line preamp slot that uses the same tubes. I just don't want to repeat this procedure every other week or so.

Last year I put NOS Brimar military in there so they should be good for a very long time. I didn't like these Brimars, by the way, they had a recessed midrange, nothing like Mullards. High frequencies were good, though.

@inna - 

From the Stereophile review ... 

Inside, all signal paths are kept as short, straight, and direct as possible in relation to the front and back panels, with power tubes and output transformers to the rear, and a centrally located switch in front of the power transformer to choose between ultralinear and triode operation. To the left are four 12AX7 tubes (two for the line stage, two for the moving-magnet/high-output moving-coil phono stage), and on the right are three 12AU7 driver tubes.

So I guess my question would be, if you are not using the phono, are those tubes engaged and does it matter whether they are good or not.  

Rich 

I think, they are somehow engaged, but I don't really remember what Kevin said except that they should be there. He didn't say it didn't matter whether they were good or not.