TPA3136D2EVM: Resistive load max p-p voltage

I had one last question about the single ended p-p voltage measured across

the resistive load.The load is 4 Ohm, 3W. The max p-p voltage across the 

load should ideally be 9.78 V. This translates to max Vin p-p = 0.49V for this 

class D amplifier.

I tried Plimit = 1.25 V and Plimit = 2V (both scope waveforms attached). There is

barely any difference in the output p-p voltage. It falls short of the ideal max by 1V p-p.

What are likely causes? How can this be improved?

Edited to add: DC power supply to the EVM is 12V.

Thank you,

Priya

PLIMIT = 1.25V

PLIMIT = 2V