QU 32 mix output seems lesser quality than the main L/R outs ??

Hi,

Hope someone can assist with something I have noticed after studio recording with the QU 32 for a number of years.

I have been sending audio to DAW via the mix 5-6 outputs while monitoring the full mix on L/R thru the Alt outs.

I have noticed that the outputs from mix 5-6 ( and I’m presuming all the mix outputs ) is dull and not of the same sonic quality as the main L/R outs. I only noticed this when I recorded a full mix onto two comparison stereo channels to have an A/B comparison with one from the mix 5-6 outs and the other from the alt out with L/R selected as the source.

I tried also recording the same full mix from the alt outs with mix 5-6 selected as the source and its the same lesser quality than the main L/R mix.

By lesser quality I mean its slightly duller and seems less detailed to my ears.

Anyone have any experience of this and any suggestions what might be going on ?

Thanks