Mitigating effects of low quality material

In a few weeks I'll have a dj-only gig where the majority of the material played will be a ghetto-style music with very poor mastering and quality, sometimes the only releases are youtube or 128kbps mp3. Everytime I do such a gig the bass simply goes away, a lil EQ sometimes help, but when the DJ drops a pop track on 320kbps and pro mastering you can see the subs clipping and night and day difference.

Now this gig a lil more hi profile, I'll have access to more equipment and was thinking of asing the provider for a DPR 901 or TC finalizer, do some sort of dynamic EQ/ multiband compression, maybe some analog pre to try and get some more "oomph" from the tracks, I know I can't bring quality, just want to make things a bit more equal on the dancefloor.

Any ideas?

If by chance the *only* thing wrong is that the bass and kick drum aren't loud enough and the track as a whole has too much dynamic range/isn't normalised to 0dBFS, then yes some added low end EQ and overall compression might improve the sound in the club. But I would say that's rare. Normally you would just end up making it muddy/boomy/too loud by such techniques.

Although you say the bass "just goes away" - that sounds like it could potentially be a phase problem? You could try inverting one channel and then summing both to mono, see if it makes things better or worse...

I had someone plug their laptop into my mobile rig via a mono-sum cable the other day, and the sound that came out was super tinny, no bass, not even any low mids. 

We suspected the headphone socket might be duff. But, on digging into his Windows sound settings, we discovered that "Dolby surround" was activated. Turning it off restored normal, full-spectrum sound! 

So it seems that Windows can sometimes "intentionally" output out-of-phase left and right channels - I've heard it on several Youtube videos too - could be that some of these tracks are affected by a similar thing? - maybe a "surround sound" plugin...