Morning folks,
Once again, thank you all so much for your input. I’m an absolute novice when getting this techie on sound production and your advice has proven invaluable so far.
So, here’s the latest update. I have tested all of the mics, one at a time per channel and they are each fine however when you plug them all in at the same time, this is where the problems start.
My personal opinion is that each mic requires phantom power as they’re condenser mics and the more mics you use at one time, the more the power is split (I know I’m staying the obvious here!). I’m not sure the mixer has enough “juice” to provide adequate power to all six mics in one go and therefore it prioritises some channels over others which creates the unbalanced sounds.
I think in this particular instance, channels 4 and 5 are the worse performing ones (which Sam Spoons has mentioned, has less dB than channels 1-4):
Sam Spoons wrote:The manual says all 6 mic inputs have spook but 1-4 have compressors and +60dB gain while 5&6 have no comp and +40dB.
As I stated earlier, this then means that to be heard on those two channels, I have to whack the gain up to pretty much max to be create the same recording level as mics 1-4 but that means lots of “white noise” being heard.
I think my only, and probably easiest, option is to take the phantom power out of the equation and just use dynamic mics. Given we’re six friends who create a podcast, I want a good, clean sound but I don’t think we’ll be giving our day jobs up anytime soon!

If you have experience of using dynamics and can recommend one at a good price, do let me know.
Thanks again,
G