I have a 65' Band Master head with NOS 7581 power tubes which are noted for their clean headroom. Through my 2X12 cab with Weber C12N Ferromax speakers (12F150 25 watters), the clean tone is warm and fat sounding as tung was describing. It's the tone that many people think of when talking about clean tone, as opposed to a sterile, flat sounding clean tone that's not very appealing to the ears.