Question about paring cabs

[ramiroelliot]

So i have one of the little 20W Joyo amps and i use it with a 16ohm 2x12 speaker cabinet. This cab has a cab linking output and im wondering if it would be safe to use with the addition of an 8ohm little 8" orange cab i have sitting in the closet. And if it is, would it even be beneficial sound-wise? Would it be louder or maybe more or less headroom? Im new to all this.

[Kaz Kylheku]

If we do the paper calculation, it is almost certainly safe. When you connect the extension cabinet that's almost certainly in parallel. You're putting 8 ohms in parallel with 16 ohms. The effective impedance is then 5.3 ohms. Less than eight by more than four. If the amp can take four ohms it's fine.

How loud things will be overall and relative to each other, only experiment will show. The most important factor is how efficient the speaker is, and especially how efficient in the frequencies off your guitar tone that the air sensitive to and that appear loud.

A 102 decibel 8 ohm speaker will be a lot louder than a 97 decibel 8 ohm speaker.

So when you have various mismatched speakers, it's anyone's guess. If you know the dB sensitivities, you can have a pretty good idea about which speakers will dominate.

[g1]

Not sure the exact model you have, but the 20W Joyo I found online was minimum 8 ohms.  If that is the case for your amp, it would likely overheat and shut down or burn up with the extra load.
The other issue is that the 8 ohm cap will hog the power.  It will get twice as much power as the 16 ohm cab gets.  This is on top of any db sensitivity issues Kaz mentioned.
I wouldn't do it, mostly because you will be hearing mostly the 8".

[J M Fahey]

To boot, I bet the 2 x12" 16 ohm cab is WAY better than the usually cheesy 8" speaker in a shoebox typically fitted with these amps.

So even if it worked, most of the power would go to the worst speaker.

Not good or advisable.

Notice the linking jack is on the cabinet but not on the Joyo head.