Knob-tastic !

I've been trying not buy a mixer for quite a while. It's been one of those things that I know is not really vital, and yet could be very useful.

Ah... wait a minute.... I realize there may be some confusion here. There are quite a few different sorts of mixer; food mixer, concrete mixer, drinks mixer, very sociable person etc.
The sort of thing that I'm referring to is a mixing desk for music. This is the thing that you see at rock concerts, often somewhere near the back of the hall, with some ruffian wearing last year's tour T-shirt, hunched over it, intently tweaking the sound balance of the various instruments and mics.

The sort of gigs that my band, 'Nightflight', plays wouldn't normally require a mixing desk in the "auditorium". We tend to play pubs and small functions where space is often limited to the point where it's difficult enough to get the musicians set up comfortably, without trying to fit in another table-full of stuff plus the multicore cable that you need to link it all together. We run a small PA mixer, with built-in power amplifiers, "on-stage", which we can adjust to get the sound balanced. It's less than ideal, but is pretty effective and comparatively pain-free.
The excuse for getting the new bit of equipment, is the forth-coming "Significant Birthday Party" for Blight-of-my-life.

As part of the festivities, we've been lucky enough to get local blues band, 'Amandla', to play. They're good mates of ours, and have been around for years; if you think that "The Blues" is just a twelve-bar, with some miserable sod moaning about how he "woke up this mornin' ", you need to see this band.
I had thought, that as 'Amandla' were playing, I would be able to have the evening off.
This, of course, was incorrect. Blight' wants my band to play as well.
This is actually quite a nice thing to do, although technically it is potentially fraught with difficulty. We obviously won't be able to get all the gear for both bands into the available space, but fortunately the guys from 'Amandla' are happy to let use use some of their stuff, so we can reduce our gear to a minimum.
You may ask, "So if you're going to need less stuff to play, why are you buying a mixer?"

"Errr... 'cos it's got lots of knobs, and I've always wanted one."

But if Blight-of-my-life asks you, tell her it's to make it easier to get the sound balanced for the bands at her party.