Only if the line preamp has a true Tape monitor function. That is, when a source is selected and sent to the tape record out, selecting tape monitor substitutes the Tape In for the selected source without disconnecting the source from Tape Rec Out.
In the 80's, this was common to every pre-amp, integrated amp. Today, it is rare.
My Halo P3, for example, has Tape Rec Out/Tape Play In, but if you select "Tape" you can only get an input from the tape Play In and the record source is disconnected.
However, the P3 gets around this by having an "External Processor" loop, which is effectively a place to splice in an external device between the source and the volume gain control sections of the pre-amp.
The obvious alternative is to put your EQ between your Line amp outs and your Power amp inputs. If it's got a gain of 1, should be no issue.