Msstl's number one response is probably right on...I would have contacted the MFG and asked what tubes in the unit respond most to rolling...just changing tubes out doesn't always change the sound...the KRads are great BTW
Tube Rolling - No Change in Sound
In my Wyetech Opal pre, I substituted NOS Ken Rad VT231's for JAN Philips WGTA's in the input stage, expecting more body and warmth to sound based on Ken Rad reputation. But nothing has happened; I perceive no audible difference from the switch in tubes! What's up with this? This was my first foray into tube rolling.
Neal
Neal