No need to apologize. Most guitar players never have to deal with matching amp heads to speaker cabinets and the math (!) involved.

First, I’ll give you the quick answer. Then, I’ll explain it. Use a speaker cable, not an instrument cable although that will work without any danger. Plug one end of the speaker cable into the jack on the back of the EHX MIG-50 labeled 16Ω. There are three jacks on the back of the MIG-50: one labeled 4Ω (4 ohm), one labeled 8Ω (8 ohm), and one labeled 16Ω (16 ohm). Make sure you use the one labeled 16Ω. Plug the other end of the speaker cable into either jack on the back of the EHX 2×12 cabinet. The EHX 2×12 is a 16Ω cabinet and you want to plug it into a 16Ω output on an amp head.

Now, for a bit of math and a couple of rules. First for the speaker math.

If you connect speakers IN SERIES, you just add up the impedance of all the speakers.

4Ω + 4Ω in series = 8Ω
4Ω + 8Ω in series = 12Ω
8Ω + 8Ω in series = 16Ω
8Ω + 16Ω in series = 24Ω, etc.

Series is easy. In fact, the EHX 2×12 cabinet is almost certainly a 16Ω cabinet because it has 2 8Ω speakers wired internally in series.

Now, a bit tricker, but stick with me. You might need it later. You’ll see why.

If you connect two speakers OF THE SAME IMPEDANCE in parallel. You simply divide the impedance by the number of speakers you have connected.

Two 4Ω in parallel = 4Ω/2 = 2Ω
Two 8Ω in parallel = 8Ω/2 = 4Ω
Two 16Ω in parallel = 16Ω/2 = 8Ω
Four 16Ω in parallel = 16Ω/4 = 4Ω, etc.

The calculation for parallel connected speakers of DIFFERENT IMPEDANCES is a bit mor complicated, and you can easily find speaker impedance calculators online. Most people never have to deal with hooking up speakers of different impedances in parallel, so let’s just ignore that for now.

So, why do you care? The two jacks in the back of your 2×12 are connected in parallel. If you are only plugging a single cabinet into the back of your MIG-50, you can use either jack. However, if you decide to plug another cabinet, like a subwoofer, or a horn, or a Marshall cabinet, or a Fender speaker cabinet, or another EHX 2×12, or whatever, into your MIG-50, you would actually do it by plugging it into the second jack on your 2×12 cabinet. Then, you would be running them IN PARALLEL, not in series even though it might seem like it since you’re plugging one into the other. The jacks are wired IN PARALLEL and you would have to use the “speakers in parallel” calculation to figure out the total impedance.

Let’s say you plug another EHX 2×12 into the other jack of your first EHX 2×12. You would now be running two 16Ω cabinets IN PARALLEL, so the total load would be 8Ω. That means that you would now plug into the 8Ω jack on the back of your MIG-50.

Now, for some important rules.

1. You should always try to match the output impedance to the impedance of the speaker. If the speaker is 16Ω, like the EHX 2×12, use the 16Ω output jack on the head. If the speaker is 8Ω like the majority of other speaker cabinets out there, use the 8Ω jack on your MIG-50.

2. You can safely plug a lower output impedance into a higher speaker impedance. If you can’t exactly match the impedance of a speaker or set of speakers, you can go from lower to higher. Like if you find a weird OLD 32Ω P.A. speaker that you want to try with your MIG-50, you can plug it into any of the output jacks on your MIG. 16Ω would be best because it’s closer, but any are “safe” because you CAN go from low to high. There will be a sacrifice of volume and tone, but it will work without frying your amp. Of course, you can still blow your speaker if it isn’t rated for the right amount of power and you turn it up too loud.

3. You cannot safely plug a HIGHER output impedance into a lower speaker impedance. Do not plug an 8Ω Marshall cabinet into the 16Ω jack on your MIG. Plugging into a lower speaker impedance can overheat your amp and fry some circuits depending on the difference in the impedances, the volume, and how long you play. You won’t INSTANTLY fry your system, but it puts a big stress on your system, so just don’t do it.

4. Don’t use more than one output jack on your amp at the same time. It might be tempting to plug a 16Ω cabinet, like the EHX 2×12, into the 16Ω output jack AND an 8Ω cabinet into the 8Ω jack AT THE SAME TIME. This MIGHT work, but generally that’s NOT how it works. I don’t have the MIG and I haven’t looked at the wiring, but those jacks are not usually intended to be used simultaneously. Don’t do it unless the manual or a tech says specifically that you can. Usually those output jacks are wired in such a way that if you were to use them simultaneously, you’d have to do some tricky calculation to figure out what kind of load they are actually expecting to see, and it would be different for each input. You’re better off “chaining” your speakers together and doing the calculation to see which SINGLE jack you should plug into.

5. Don’t assume a cabinet is 8Ω. Most are, but many aren’t. If you don’t see a value somewhere, don’t assume.

6. Don’t assume two speaker jacks are parallel. In some speakers, two jacks are wired in series. Don’t assume.