Hi Nr9, I have a Berning Switch mode tubed powered pre-amp ( yes a tube switcher), a Berning Switch Mode powered tube BAM, (Don't ask and I lent it to profone, who still has it and does not want to give it back :)) and a Berning SMP supply Headphone amp, two Berning mono amps with 1 Farad of power supply capacitance each also with switching power supplies without adjustable gain and noise is absolutely not an issue.
I have had complaints with a couple other pre-amps with regular power supply's as well being noisy ( and tested as such), it's an issue of sometimes higher residual noise of the pre-amp design or sometimes noisy tubes, which a most other power amps do not have the sensitivity to show up.
Our first switch mod pre-amp was in 1984 the TF-12 and TF12B, B for Balance, No issue with noise on the ZH-270 with the TF-12.
This is one of the reasons that we have the adjustable volume control on the ZH-270 and why we would not do amps without these unless we do our own matching pre-amp.
You may want to reduce the sensitivity of the amp by reducing the gain on the volume control.
I have had complaints with a couple other pre-amps with regular power supply's as well being noisy ( and tested as such), it's an issue of sometimes higher residual noise of the pre-amp design or sometimes noisy tubes, which a most other power amps do not have the sensitivity to show up.
Our first switch mod pre-amp was in 1984 the TF-12 and TF12B, B for Balance, No issue with noise on the ZH-270 with the TF-12.
This is one of the reasons that we have the adjustable volume control on the ZH-270 and why we would not do amps without these unless we do our own matching pre-amp.
You may want to reduce the sensitivity of the amp by reducing the gain on the volume control.