Want all the growl you can get? This is the High Gain Option Retube Kit for the Mesa Boogie Bass Strategy 88. For the front end this kit contains three handpicked High Gain ECC83S's with two of them being current balanced for the phase inverters. The default power tubes are a matched octet of the JJ Electronic KT88's however you can configure this kit to use an octet of the JJ 6550's for a little earlier breakup by clicking on the "Customize" button!
These amps are adjustable bias and no tools are needed. The KT88's and 6550's bias the same.