Not to come off sounding sexist with my example, but tone in general can be like taste in women. You might see a redhead that everyone thinks is beautiful, but they aren't your type of woman so she has no appeal to you. I happen to think redheads are amazingly attractive, but that's because they fall under the category of women I like. You cannot objectively say in 100% inarguable confidence that one amp sounds tonally superior to another, you can only state which you find better or more enjoyable. I own tube amps and solid state ones and like them for different things. I'm warming up considerably to GK amps because I can get the hint of grind I like from tube amps and then amplify it considerably from there without worrying about more distortion coming from the power section. I don't have to look as hard or worry about volume when going for the sweet spot that I like. Some people like that extra power section breakup, but it doesn't work in the band I'm in right now, not to mention it's easier to maintain "my tone" with the GKs at varying volumes.
I happen to own a 70's receiver, turntable, and original speakers that my dad gave to me when I moved out. I really enjoy the character and present midrange that comes through on the stereo and I don't hear that in most CD players or audio receivers/speakers these days within a reasonable price range. I could make the assertion that it having lower THD than most modern receivers and not being uber mid-scooped means it sounds better, but some people don't feel that way. I realize there are absurd levels to take this to (i.e. - Apple earbuds will not sound as full as a set of Sony studio mixing headphones), but we're talking about reasonably well-made bass amplifiers here. I'd venture to say GK, Genz Benz (when they were still around), Markbass, and countless others aren't making substandard electronics---but that's my opinion.
