I just carried out a simple experiment. Using a Db meter app on my iPhone set three metres away from the amps. I did a Decibel comparison. The guitar used was a Strat with the volume knob set at three, the selector set to neck and middle pickups combined. A C scale was played and one C chord.The guitar setting and what was played was repeated for each amp. On each amp the volume control was set at 5 (halfway) and the three tone knobs also all set at 5. The first amp, a Frontman 212R, solid state 100watt RMS, two 12" speakers gave a peak Db reading of 105. The second amp a Frontman 25R, solid state 25 watt RMS, one 12" speaker gave a peak pf 96Db. The third amp a proprietary Chinese made valve amp (2 EL84 power tubes, 3 12AX7 preamp) rated at 20 watts RMS with one 12" speaker gave a peak reading of 106Db. (Both the channel and master volumes were set at 5) When the valve amp volumes were turned down to 3 the Db peak was 100 Db. Those readings were all at the indicated halfway volume capacity of the amp. In all probablity the max volume readings would be somewhat different. However, i gig with the Frontman 2121R set at 5 and it is well audible over a heavy handed drummer. The experiment would seem to indicate that a 20 watt RMS valve would be pretty close to a 100 watt RMS Solid State in volume/loudness capacity. The 25R struggles to be heard over a drummer but is quite capable when no drummer is present. The diference between 96Db and 105Db does not look like much on paper but in practical reality there is quite a difference. I'm curious as to what results others would get if they carried out a similar test.