Does this mixer need an amp to drive it or is it powered

you need a power amplifier between the mixer and the speakers to actually drive the speakers. You would have to choose which amp to use (the manual, found here: http://www.bose.ca/controller?url=/shop_online/speakers/stereo_speakers/acoustimass_5/index.jsp#manuals suggests between 10-200 WRMS for power), and thus would have to determine the cabling options depending on the amp you choose, but...go from either the MAIN or CONTROL ROOM outputs of the Mackie mixer into the inputs of the power amp. Then go from the outputs of the power amp to the inputs on the Acoustimass bass module, which also runs the Acoustimass satellite speakers.

First it is certain that you would not want to plug both outputs of the stereo power amp into one speaker combining both channels into the same speaker. (see image from manual below - also link to manual)

Next I would be very concerned about only using the one side of the main amp out as it could cause an unbalanced load, or you could be driving the load into dead air connection and any of these conditions are destined to cause premature failure of the power amp.

Taking a quick scan of the manual for this unit, it appears what is pretty common to most powered mixers, hook up two matched speakers/loads to each chanel of the output.

Your best bet is to shed those monster cabs, there really is no need for them especially with this sized powered mixer, and get yourself a nice pair of full range cabs like EV1202;s, EV SX300's, or some nice 2 or 3 way 15" JBL's/

Just my opinon.

Link to Yamaha EMX 312 Owner's Manual:

Yamaha EMX Series Owners Manual

You have two aux sends on that mixer so quite easy to use one of those to feed the external power amp. You could have one set of spkrs connected to that amp and another connected to the powered mixer. This would give you full independent control over each set.

Looks like it takes regular home theatre speaker wire. If this is a powered speaker (like a JBL eon g2), then all you need is a passive mixer, and connect the speakers to the mixer. If this is not a powered (amplified) speaker, then you will need an amplifier to boost the sound source and drive the speakers, so you would connect the mixer to the amplifier, then the amp outs to the speakers.

You CAN drive the power amps from the main amp inout jacks BUT the rest of the inout of the 8600 would be dead then. You can connect the L and R from the FX24 to either the media RCA jacks or into the channel9/10 jacks. FOr the latter, use TRS cables. Leave the two selection buttons in the up position.

The output jacks are PSUEDO balanced so use TRS cables and you should be able to drive two amps from each with no problem either as a WYE or daisy chained connection. The PSUEDO balanced connections do NOT drive differential voltages, but tie the return to ground through a 120 ohm resistor. It is imperative that you power ALL the amps and the mixer from the SAME receptacle or power conditioner. If you don't do this, expect lots of hum and risk of ground bounce damage to your equipment. Run extension cord if you need to.

The MG24/14FX is a mixer only, with no amplifier built-in. It can't drive speakers directly. You'll need powered speakers or separate amps and speakers.

You can add extra amps driving ADDITIONAL speakers... you CANNOT parallel amps driving the same speakers.

Drive these seperate amps from the MAINS OUT connnectors using TRS and balanced lines to those external amps.

Intermittent problems cn be a real pain to find... BUT I want you to verify your use of the mixer and its connections as one can cause the output drivers to latch up due to ground bounce.

Make sure your outputs go to the power amps AND into balanced inout at the amps... either XLR or TRS connectors.

Make sure that the amps are POWERED from the same receptacle as the mixer... even if you have to run power back to the mixer. If you power the mixer from a different receptacle at the other end of the room, ground bounce of the safety ground MAY exceed the common mode drive of the mixer and cause the output drivers to latch up or even be destroyed!!!

The mixer is strictly a mixer. You would need to amplify to drive speakers. Used as a mixer it is fineand would support up to 4 mics.

It does have phantom power for use with condenser mics if needed.

Please use balanced lines (TRS) when connecting to the external amp.