Rode m2 + mackie onyx blackjack

Yes, get some TRS to XLR (Male) cables or adapters and plug them into either the monitor or alt outs, set your routing and levels and away you go.

This is available at http://www.mackie.com/Products/onyxblackjack/pdf/Onyx_Blackjack_OM.pdf

I ASSUME that you plugged your guitar into a DI box that then used BALANCED XLR cable to the Mackie board??? The guitar generates line level and the Mackie board inputs are mostly mic level... you will get distortion if you overdrive the Mackie board. You could try going into line level jacks, HOWEVER if you go any distance balanced interconnects must be used. Even the line level jacks require using TRS balanced cables. Try is using a DI box, and preferably one with a gain switch. Also fiddle with the ground lift switch on it for least noise or hum. I use the LiveWire brand DI boxes and they seem to work fine. Then it is important to set the gain with the trim on the MAckie so you don't clip. Also be aware that an acoustic guitar can "hear" speakers and you can get feedback or regeneration that will sound like you are in a cave.

You haven't told us where the "sound" is coming from... If you are ONLY plugged in one channel that is all that will be recorded. We can't guess at how you are setup. Please provide an adequate description. If you only have a mono signal to start with, then get a WYE connector and jumper to the second channel.

Check the cables. If one lead of an XLR-XLR cable is shorted to ground, 6 DB gain is lost. You haven't really supplied enough information regarding cables and model of the manual mixer for us to help much. Do check that ALL of your audio interconnections are BALANCED lines either XLR to XLR or TRS cables. Grounding one side of a balanced line reduces gain 6 DB. Try swapping mic cables and channels to test where the problem is in the system.

Make sure ALL of the interconnected equipment is powered from the SAME receptacle to avoid ground loops due to the safety ground. DO NOT Use two wire power or use ground lifting plug adapters. Make sure you use balanced lines, either XLR or TRS cables. Do NOT use TS cables.

yes - trs or xlr inputs will give you the same result, as long as you use the correct cables.

Make sure the mackies are off when you plug them in or you'll get a nasty thump. Equally, make sure the volume is down on your interface initially.

Make sure you are using BALANCED line to this... XLR connections boyh ends. Make sure ALL interconnected devices are powered from the same receptacle or power conditioner. Test your cables... they do go bad. This unit REQUIRES line level input. Do NOT expect a mic to drive it directely. Make sure your mixer uses the XLR outputs and is powered from the same receptacle, even if you have to run an extension cord to it. This is a bi-amped speaker so there are independent amps for high and lows. With nothing out and known good in there is very little electronics before the signal is split to the separate amps. At line level, your volume control should probably be about 2 o'clock with the EQ's straight up flat.

This is not hard to do, but it will require some adapters. Hosa company makes adapters to accomplish this. For example, if your Stereo mic has "1/4 inch male phone plugs" Hosa makes and adapter that has 1/4 inch female plug to Male XLR connectors. The Mackie, and just about every mixer in the world these days has Female XLR connectors for it's microphone inputs. So that will handle tha.

I'm not sure what you mean by the "combo" amp. If it has XLR inputs you can use Tip Ring Sleve male output jacks to the output. If your amp as conventional 1/4 inch female input jacks. Than a simple
1/4 inch Male to Male Guitar Cable will work fine. DON'T USE A SPEAKER CABLE as it is uninsulated and you will get 60Hz hum.
I hope this helps,
That looks like a great quality mixer you have!
Happy New Year,
Mark

Likely you haven't got the levels set properly. Start with the trim controls (head end gain) Make sure you are not clipping there. Also verify you aren't overdriving your amps. Remember that the outs are line level, not mic level so the gain oof following equipment needs to be set for line level.
ALWAYS USE balanced audio line from this unit... either XLR or TRS type cables. ALWAYS power ALL interconnected equipment from teh same receptacle or source to avoid ground bounce damage to circuitry. You don't say what you are using to record with. Make sure it has balanced inputs. For instance, connecting cables from this to the audio input jack of a PC which is unbalanced would be a disaster in audio quality. There would be a problem of levels and the unbalanced thing... You haven't given us enough information of your hardware configuration to analyze the problem more than what I have said here.