Hi Hzhu1920, have you tried the volume control at 1PM-2PM on the Berning and then use the pre-amp to adjust the volume, if the ZH-270 you have has the stepped attenuator, meaning that it clicks as you turn the volume, you will want to turn the knob to 3 or 4PM on this amp, please try this, assuming that you are using low feedback, if medium or normal you can turn the volume up much more on the ZH-270.
If you are going to the Stereophile show, the ZH-270 with the Steelhead will be in room 381.
I'll be more than happy to call you and discuss this and see what tubes you are using and how old they are and more.
Allan
David Berning Co
If you are going to the Stereophile show, the ZH-270 with the Steelhead will be in room 381.
I'll be more than happy to call you and discuss this and see what tubes you are using and how old they are and more.
Allan
David Berning Co