Looks like clue time.
Al Kooper was a good guess.
Like Al Kooper, this guy was/is a terriffic studio musician.
To this day, he can be found listed on some of your favorite CD's personnel.
And, like Kooper, he was also in a band that has played live.
Also... Like Kooper (associated with Mike Bloomfield), This guy was associated with what is considered to be one of the
greatest guitarists ever.
In fact, he co-wrote many of the songs on this guitarists finest album.
As well as was the co-singer on that album.
And, like Kooper is probably better known for playing the keyboards/piano than the guitar. (Okay so Kooper was known more for the organ, close enough
Hope this kinda helps.
If not, more clues later.