Begin with the source, and switch the left/right interconnects until you figure out which component is the problem.
For example - connect the Right output of your CD player to the Left input on your pre, and connect the Left output of the CD player to the Right input on your pre. If this setup results in a dead right channel, your CDP is to blame.
If, after doing this, you still have a dead Left channel, repeat the procedure for the pre to power connection. If this results in a faulty Right channel, instead of Left, then your preamp is the problem.
If the Left channel is still dead, then switch your speaker cables (ie, connect the Right output of your power amp to your Left speaker). If this move switches the dead channel from Left to Right, then your speaker is busted. (although, in this case I would have someone take a look at the amp to figure out why it ruined the speaker).
I am not too familiar with tubes and don't have any good advice as to isolating the problem if the tubes are at fault. I am sure there is some way you can switch paired tubes from one channel to another... but ask someone else, who knows what he's talking about.
For example - connect the Right output of your CD player to the Left input on your pre, and connect the Left output of the CD player to the Right input on your pre. If this setup results in a dead right channel, your CDP is to blame.
If, after doing this, you still have a dead Left channel, repeat the procedure for the pre to power connection. If this results in a faulty Right channel, instead of Left, then your preamp is the problem.
If the Left channel is still dead, then switch your speaker cables (ie, connect the Right output of your power amp to your Left speaker). If this move switches the dead channel from Left to Right, then your speaker is busted. (although, in this case I would have someone take a look at the amp to figure out why it ruined the speaker).
I am not too familiar with tubes and don't have any good advice as to isolating the problem if the tubes are at fault. I am sure there is some way you can switch paired tubes from one channel to another... but ask someone else, who knows what he's talking about.