Another piece of Advice I have received from Bowie:
If you encounter cross talk, than it's most likely the metal shielding on the tube that is picking it up. The tube shield can be removed temporarily/permanently if you like. This will also increase the High Frequency response.
To check for the cross talk: Plug the mic into channel 1, turn up the gain and output to decent levels (half way), turn the phantom power IF NEEDED, now plug in your headphones straight into the output of the channel 2, turn the levels on channel 2 to the same level as channel 1 (channel 2 doesn't have a mic plugged in, just your headphones).
Talk/speak/sing into the microphone on Channel 1. You shouldn't hear ANYTHING coming out of the output of the Channel 2. If you hear static buzz everytime you sing/speak into the mic, you are getting a cross talk.
Cross talk is basically when you have one of the tubes on the opposite channel receiving interference from the first channel.
Some tubes are more prone to having this issue, some not at all. You can remove the tube shield which can help the situation on the tube receiving the crosstalk. (In our scenario Channel 2, since the mic signal is on Channel 1)
