Noted, but those amps are known to work well for bass. Apparently Entwhistle used one too? The speaker/cab is probably more important than the actual amp head, especially back then. Bass & gtr amps weren't drastically different from one another, compared to today.
I guess we have the Yessongs release to compare sonics: same shows
On his first tour in the USA, Squire, Sunn loaned him a bass head (possibly a Coliseum Bass model) and a 4x12 cab to use. He didn't like the sound. So they swapped him the Coliseum Lead model instead, which he did like.. so much so that when he got back to England, he went to Sound City and got a used one for himself (previous owner: Eric Clapton). So the head did matter. By the time the Yessongs tours were recorded -- he was using dual Sunn 6x12 cabinets with that head. He stuck with this rig until around 1976.
And John Entwistle was, obviously, another bassist who liked a lot of treble.