QSC 1622 Poweramp / Preamp Info

Hey All,
Long Long Long time thread stalker, first time poster.

I have am putting together a somewhat "budget" rig for some home use and also a few gigs a year. I know i have been trawling the second hand market and have come up with a few items so far.

I have gone with the Preamp/Power option as i have a home theater at home which has just had an upgrade to one of the power amp and i would like to use it for the bass (saving $$)

It is a QSC DCA1622 (running Bridged 8ohms) into a Behringer bb210 600watt 8 ohms cab (i know there cheap but only cost me $50AUD).

now due to reading lots and lots of threads on here i am wanting to make sure i am getting a preamp that will provide the right input for the poweramp.

at this point of time i have a Ashdown Hyperdown - Nux Ampforce - Toms line Matchbox DI. running into the PA. it sounds good and clean, for a cheap setup i am surprised. but lack a bit of volume.
Could this be due to the low output of the pedals?

would the 20db+ on the DI help (it makes it louder, just not sure if its the right thing to do)

I am looking for a preamp panel that i could use but not really keen on the sans amps, as i see thats what is always recommend.

or can i use what i have but just fine tune?

any help would be good