All competently designed amps of sufficient wattage and current, low noise and distortion, with low output impedance will sound like same - Peter Walker of Quad fame.Funny thing- there were no such amps around when Peter made this comment.
<rant>
Why? Any amp employing feedback back in those days simply did not have enough (and gave feedback a bad reputation that has lasted to this day). Not only did they not have enough, at the time is wasn't even apply the amount of feedback needed, else the amp would oscillate. So most companies didn't do it, knowing full well there was a problem.
This gave solid state amps a reputation for being harsh and bright because that is the result of insufficient feedback. Quite literally that is why tubes are still around. I'd hardly call that 'competent' since feedback is all about control theory which has been well understood for a long time.
</rant>