adding a subwoofer to my 2 channel lanai system

If my question has been addressed, my apologies.
My living room 2.1 system is powered by a Mcintosh MA6500
integrated amp. The speaker 2 section is dedicated to a 2.0 system consisting of two in ceiling speakers (8 ohms). I would like to add a in ceiling subwoofer driver.
How would I do this?

Thanks in advance.
I don't know. Usually around here people aren't discussing in-cieling setups. However, here are some aspects for you to consider.

Subwoofers are heavy devices. Mine weight 100 lb each. Granted these are heavy ones, but the drivers alone are also heavy devices.

Subwoofers tend to be large. Of course how large depends on the size of the driver, whether you want a sealed (larger) or ported design, and how low you really want it to go. Mine are 2 cubic feet internal volume with a 12" driver, in a sealed enclosure, but are servo-driven - otherwise the box would have been a different size. How much space do you have between your false and hard ceilings?

It is generally accepted we cannot detect directivity below around 80 Hz. So placing a subwoofer on the floor might make life easier. If aesthetics is the constraint, consider buying a kit, such as Rythmiks, and building a subwoofer that looks like an end table or other decor piece. I bought these kits, but because I wanted to build a really heavy, sturdy enclosure.

I hope this triggers some thoughts.

It appears the MA6500 is stable to 2 ohms, but still best make sure there won't be a problem.

What is the impedance of living room speakers, and does the .1 subwoofer have it's own power?

Here is an example to show you a proper way to install a single in-ceiling subwoofer, assuming you want it powered by the MA6500.

OEM Systems

Use the dual voice coil model of the woofer and 2 crossovers, one for each channel, then wire using the Crossover Option 2 diagram on page 16 of the manual.

All of the above can also be accomplished by using a SpeakerCraft 8.2 BAS. This in-ceiling woofer is a dual voice coil and has the crossovers mounted on the back. It also has a phase switch and the crossover is adjustable.

Just thought of another issue, it will be important to choose a woofer with the same sensitivity of the other in-ceiling speakers, although a 1db difference will likely not matter.
Tls49, the living room speakers are 6 ohms. I'm using a powered REL sub with a pair of Monitor Audio GR20's.

SpeakerCraft reviews are depressing at best.

I realize that putting a sub in the ceiling is not going to be revolutionary, I'm just trying to add a little bass to my lanai listening.

Since living room speakers are 6 ohm with a powered sub, impedance will not be a problem.

As far as the SpeakerCraft and OEM Systems, these were just shown as examples of how to properly do what you were asking.

Another option would be a ceiling mounted woofer with an external subwoofer amp like these,

ICS11 Ceiling Subwoofer

M3 Subwoofer Amplifier

The subwoofer amp will need to connect to the MA6500's L&R pre out.
Thanks Tls49, I will definitely look into your
Recommendations. Thanks again for your help.