Used a TubeJuice (no longer made) and a Weber MiniMass. The Tube Juice was/is just a resistor based LPad attenuator, with a treble boost and built-in fan. Very good as LPad types go, definately need the treble boost as with it off, it lops off too many highs imho. The Wber MiniMass I highly recommend. Uses a speaker motor for the attenuation. Much more organic and natural sounding. He builds them to your order (and does sell some with favorite options on EBay sometimes). Figure 90-120 depending on what you want. The MiniMass only has a 25w and 50w version. The Weber Mass goes up from there. If you want to crank the amp and attenuate to really low volumes, then count on getting twice the wattage of your amp in the attenuator. The Weber's sound awesome imho. The only real difference with the MiniMass (and the treble boost engaged) is the tonal shift by your perceptions, because the speaker isn't pushing as much air at attenuated volumes, so it feels/percieved different than with the amp cranked and no attenuation. There is very little tone coloration.
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