If I remember right... I believe the Mode Four has a hybrid circuitry... allowing it to use tube tone... or bypass the tubes for a solid state tone. Making it a very versatile amp. However, the Mesa Rectifier is probably reveered as the most popular amp in rock and metal... Next to the Marshall JCM-800/900 series amp which was the first true metal amp out there. If you're looking at a Mesa... check out a JCM.