I also have the Coincident Frank's 300b and I have tried around a dozen 300b's and my favorite is the KR 300b xls.
They are the test tube shape and they were made in the late 90's. The Frank's are amazing with these tubes ! I have a pair of Black Treasures, they sound good but they don't match the 300bxls frequency extremes, and the bass with the KR's is rock solid.
I am using Coincident Total Victory's IV speakers with a Supratek Cortese preamp and there is definately a synergy with these components.
They are the test tube shape and they were made in the late 90's. The Frank's are amazing with these tubes ! I have a pair of Black Treasures, they sound good but they don't match the 300bxls frequency extremes, and the bass with the KR's is rock solid.
I am using Coincident Total Victory's IV speakers with a Supratek Cortese preamp and there is definately a synergy with these components.