My first thought was a tube issue as well. Tubes are frequently noisier than SS. In a pre-amp, any tube in the signal path and especially in a gain stage, should be very carefully selected for low noise. Even then, as tubes age, they can develop noise problems.
I find the tube sonic so appealing, that I am willing to sacrifice a very, very low noise floor. If it isn't audible with music playing you might want to live with it.
I find the tube sonic so appealing, that I am willing to sacrifice a very, very low noise floor. If it isn't audible with music playing you might want to live with it.