Should I buy the beltpack breakout box or the combo interface?

Combo Interface

Advantages:

* Doesn't need a beltpack to function. Plugs straight into the party line like a beltpack.

* Likely the cheaper option unless you have an extra beltpack. If you only need output, the Output only version is even cheaper if you don't need level control.

Disadvantages

* It ONLY works with clear-com systems (and likely compatibles).

* Not for 2 way simultaneous interfacing, as the input feeds through to the output & will create a feedback loop. Some systems will cancel it out, but it could cause you problems.

Beltpack Breakout Box

Advantages:

* Ideal for 2 way simultaneous interfacing. Beltpack sidetone function keeps the input from getting to the output, preventing a feedback loop.

* Mic level input version allow you to plug a dynamic mic straight in. No mixer needed.

Disadvantages:

* Needs a dedicated beltpack to function. If you've got plenty that's no problem. Even if you had to buy a beltpack for the occasion, it's still the cheapest way to create 4 wire com.