First Act MA2039 Speaker Specs & Upgrade Recommendations?

I want to upgrade the speaker in the First Act MA2039 battery amp. I use the MA2039 for prepurchase check of prospective guitars found on Craigslist, OfferUp and LetGo.

What are the OEM specs on the speaker? (Driver size, mounting bolt pattern, resistance and RMS watt rating. Also need the amp's RMS rating too.)

Im looking for better sound quality to better hear any electronics issues the guitars may have plus get an idea of the basic tone of the guitar before buying it.

SPL/max volume is not required, for that i use an EHX headphone amp with a pedal or two plugged in between it and the guitar.

I use both as each can demonstrate different things better than the other.

Thanks in advance!

-Lan