Hugh rarely deigns to test fifty quid mixers!
But there are a lot of assumptions here. Mic pres on the mixers I have bought have been remarkably good. I have a Xenyx 802, now used in a bedroom for garden wildlife mics. Cheap, disposable dynamics, and the ELECTRONIC noise is well below the general garden ambient even when the wind don't blow. If you will accept that the A&H zed 10 is a passing good mixer then the 802 stands up pretty well against it. I have a Wharfedale mixer, £40 iirc from PMT. Really low noise mic pres.
People always SAY the EQ is better on expensive gear but it is all just Cs, Rs and op amps (valves and inductors might be 'cool and marketable but they distort and are expensive) We never see A/B tests. In any case the OP needs BASS CUT so the EQ is in NFB mode and even MORE linear.
Now, I am not daft. I know the top end kit is 'at the edge' and is much better built* and much nicer to use, we had this discussion in the forum post TGP amp shootout but for the modest correction the OP needs I am confident a wee Behrry or similar mixer wold be all but invisible.
*And yet, my 802 has been running, barring power cuts, since 2014!