"Was floored by how average the bass sounded."
What was wrong with Martin Turner's bass sound with his Bird?
Granted, it doesn't jump at your throat like Squire's or Entwistle's, but then WA's whole aural landscape was less abrasive than The Who's or Yes'. I think he had a nice bony, yet natural sound, that went well with his melodic playing without detracting from the twin guitar harmonies. Couldn't imagine a better fitting one really.
Martin Turner got his TBird only post-Argus (that was still recorded with his beloved Ric - which was stolen shortly after - and he would even re-record it with a Ric - on loan from John Wetton I believe - when he did another version of Argus decades later, in 2009) from Overend Watts of Mott the Hoople - he first used it on a US tour of WA (the pictures on the back cover of Argus are from that tour - after the recording).