Dual Filter, trying to equal one of a range

In Google Sheets, I have the following filter working which gives me a column range of values:

=FILTER(INPUT!$E$2:$E, INPUT!$A$2:$A=B2)

And a second (temporarily seperate for testing) filter working which gives me a column range of values:

=FILTER(PAIRS!$B2:$B, PAIRS!$A$2:$A=B2)

I want the first filter's Condition 1 to reference the output of the second filter within the same equation, as generating a new list for every row seems excessive. However, when I try to combine the two, I'm getting "no matches are found in filter evaluation."

=FILTER(INPUT!$E$2:$E, INPUT!$A$2:$A=(FILTER(PAIRS!$B2:$B, PAIRS!$A$2:$A=B2)))

How do I have the first filter condition = the output of a second filter so that everything within it's output (a column range) is considered (instead of the current working single B2)?

Another way to phrase this would be, how do I have a filter condition = everything within a range?