I just found this online and it's kinda freaking me out: "Half power mod – Pull out two 6L6 and disconnect 1 speaker. Pull out the two inner 6L6 tubes and you have a ~40-50W amp. You should/can also disconnect one of the speakers to not have an impedance mismatch. The Twin reverb output transformer is designed to work most efficiently with the following impedances/loads and tube power configurations: 4 x 6L6 -> 4 ohm speaker load. And then comes the standard Fender +/- 100% tolerance. 2 x 6L6 -> 8 ohm speaker load. And then comes the standard Fender +/- 100% tolerance. The plate voltage will increase a little when two of the tubes are removed. Ideally you should have the amp re-biased to not run the two remaining tubes too hard. The voltage levels on the plus- and minus-sides of the output transformer’s primary circuit remains the same whith two and four 6L6 tubes. But the delivered current is doubled with four tubes. Hence, the power is also doubled. Power (Watts) = Current (Amperes) x Voltage (Volts). This mod is a must-know survival trick for all Twin owners." via http://fenderguru.com/amps/twin-reverb Has anyone tried this / can recommend it? I never heard of it before, but I was planning on retubing and getting new speakers for mine, so this would be a nice way to save money and accommodate to the volume i play at.