I'm new to the Ampeg camp and it's like I can stop searching now. Sit me down with a Precision through an SVT and it's like all that scrabbling around is over. Unlike Bono I found what I was looking for.
I also believe Trace Elliot has a special tone and Eden amps have a character all their own. Behringer and Markbass, Orange and Carlsboro - all distinct, and I've gigged with them all and more - but you know what? I bet you any money I could not tell them apart in a blind test. At least I couldn't tell which was which.
Even the valve Ampeg sounded OK but nothing special when I first plugged in, but once I played it with the band it just oozed class throughout the whole sound. It needed that context to make sense. As you say, tough to describe the sound, my singer said it was like melted chocolate poured over the mix, which I rather like. Of course the thing with bass is you and I and everyone else on Basschat will make precisely the same gear sound different by what we do with our hands.