^ Shure
I have had it for about two months now and it was totaly worth the $480 usd I shelled out for it. I had to get mine with the 200 watt load upgrade to accomodate the cranked wattages of my 120 watt tube amp. I also got the 100 v AC tap which is probably my favorite thing about the attenuator since it keeps the amp running much cooler and doesnt realy affect tone.
I don't know whether or not it is any better or more transparent sounding than other attenuators on the market, but it does take a little of the bass out of the sound, mostly at very high attenuation. Despite this one drawback though, if you have an older style amp that gets realy hot when you crank it, this is the attenuator to get. With the 100v AC tap it keeps temps to a minimum and has universal ohmage allowing you to run mismatched ohmages between your head and cab with no problems. Any tone altering affects that it might have can easily be accomadated by a couple tweaks of the amps EQ, and the UA's also got a built in fan to keep it from overheating during long jam sessions.
It might be a little more expensive than the alternatives, but it more than makes up for what it lacks in affordability with its reliability, tone, useful features, and rugged build quality.
