I currently have a the WTX264 paired with an Eden EX112 4 Ohm cabinet. If I add another EX112 cabinet, does it need to be a 4 Ohm version or can I use the 8 Ohm model?
Depends if your eden head will handle a 2ohm load if it does then you could use a 8 or anther 4 but if it doesn’t then you’ll be at 2.7 ohms and you’ll damage the head
That one cab is all you can do now. This is the drawback of getting a single cab at 4 ohms to get all the power into one box when you will be much louder and fuller sounding with a second cab than with a few (even hundreds) more watts. For your info: 8 ohm + 8 ohm= 4 ohm load. 8 ohm + 4 ohm= 2.67 ohm load. 4 ohm + 4 ohm= 2 ohm load. Never go below a total of 4 ohms with that head.