Adding a 2nd Sub to a 2 Channel System

Depending on the positioning of the subs and on room acoustics it could very possibly help to smooth out and flatten the frequency response in the deep bass region, as perceived at the listening position.

However I suspect that you would run into an impedance problem. The input impedance of the E-110’s line-level input is only 10K, and if the PL’s mono line-level output is connected to two such subs it would be loaded by half that amount, or 5K. As a tube-based design the PL’s mono output is probably driven via a coupling capacitor, which I suspect would cause its output impedance to rise at deep bass frequencies to much too high a value in relation to 5K. The result being roll-off of the deep bass content of the signal that would be supplied to both subs.

Also, while the E-110 provides speaker-level inputs which could be used, I note that its manual states that those inputs are provided for convenience only, and are not the preferred connection method.

So before going any further I would suggest contacting PL or its distributor and asking if connecting a 5K load impedance to the mono output would be suitable.

Regards,
-- Al