OP look inside your amp YOU will be surprised at the size of the TINY little itty bitty wire.. Even 12 gage with that short of a run is a push. Get the opposite of whatever your speaker cables are terminated with. Make up a jumper out solid copper with PTFE and a little armor. You won't stop smiling for the cost.
The sound, who cares. I've NEVER heard a Mac Old or New (I have both) that sounded GREAT paralleled or in series for anything other than BASS duty. It ruins the house sound of Mac. SORRY. Now that is their valve units, NOT their SS units.
The older Macs can be paralleled or put in series, STACKED!! I haven't looked at anything other than point to point and a GG model. I have No idea on Mac SS.
https://www.ebay.com/itm/303864168808?epid=1637380762&hash=item46bfb74168:g:99cAAOSwmrlU1mxnThese will work perfect, TELL the seller what your doing.. Bananas, flags or fork spades. You could use bare wire IF your speaker cables are banana. Depends on the Mac terminal. Mine are a GG and pair 64 275s.
SMALL terminal on both. Yours.. a lot better terminals.
They just work better in stereo or duel mono. :-)
Regards