I bought American DJ discolights with T20f control. I do have American Audio mixer and cd player CDI 300. 2 powered Mackie 450 speakers. How can I connect the stuff?

you should have a headphone out on the mixer or you need a mixer

Don't even go there. In my experience these are just not reliable speakers, we have had and heard of so many issues with them we sold our working ones. If one has gone sell the other working one with the dead one as spares and repairs and buy something from QSC, EV, JBL or Yamaha or even Wharfedale Pro.

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.

Balanced audio interconnects (either XLR or TRS cables from the mixer and then balanced audio interconnects from the amp daisy chain inputs to the existing speaker inputs. If the amps do not have linked input jacks, then use TRS type WYE connectors at the inputs. Then use speaker rated cables from the amps to the passive speakers.

You failed to give us the most important information... what brand and model of the mixer? Youwill use balanced interconnect lines to a balanced MAIN output jack, assuming it exists...

Make sure ALL interconnected equipment is powered from the SAME receptacle. Use extension cord if necessaary. Use ONLY balanced interconnecting audio lines as well. You have a ground loop... make sure all power connections are three wire.

Make sure you are using BALANCED audio line to the speaker AND your mixer is powered from the SAME receptacle as this speaker. One MAY have to run an extension cord back to the mixer and othe equipment, but this must be done to reduce noise and also for equipment safety. Multiple recepatacles in a building have grounding issues that can generate noise or worse damage equipment due to ground loops. If you DJ mixer does NOT have balanced outputs, use DI boxes so you can use balanced lines to your speakers. Your cables will either be XLR or 1/4 inch TRS types, not just TS type.

Wrap the post from stand w/Gaff tape until you find correct adapter.

The internal amp is in need of repair. Are there any other symptoms or signs?

Your power amp should be connected to MAIN OUT left and right. NOT the MAIN "in".

The CD is connected correctely as you described. Make sure the CD has a line level output to match the input expected by the mixer.
Note:Walkman style CD players require a special cable to go between 1/8 inch stereo to dual RCA plugs.

You have to advance the MAIN fader.

You should be using TRS interconnect cables from the mixer to your amps OR using XLR cables.