There is a nuance you may not have considered. @PeterA's speakers are an older design intended for amps of a fairly high output impedance. If you put an amp with a very low output impedance on there (solid state amp) the crossover in the speaker may not work properly and the amp could sound quite colored on it as a result. No doubt part of the reason some solid state advocates wonder what the appeal of horns is all about.
By direct comparison on such a speaker, Peter's amps could come off quite a bit more neutral.
Let's be clear about one other thing: if the solid state amp is bright, that is no less a coloration. On speakers like Peter's they may exhibit a 'one note bass' phenomena too, since the speaker was designed before the 'Voltage drive' rules became commonplace. More about this.
This is very important, speaker/amplifier matching is the key to get least coloration.
With Perfect matching you can not easily detect the amplifier sound signature or speaker sound signature.
Amplifier speaker matching is one of my three basic audio rules.