Low price but good quality DSP, i would recommend Crossfire & Rockpower brand.. usually it has build in amp, 4 channels / 6 channels / 8 channels based on models..

Remember the price tag is low & not super cheap.. because it has quality.

don't go for too cheap DSP, ussualy it will be oem brands.. the amplifier chip wont be good to power up ur speakers & difficult to get firmware & tuning software upgrades in long term usage.

if use 3 way, usually will use to power up pair of tweeter, pair or midrange & pair of midbass speaker.. this all for front. remaining 2 channel will be used for subwoofer.

i am not using my rear speaker. 3 way setup usually pleasure for the driver only.. The midrange & tweeter angle will be positioned for driver listening pleasure mostly.

its subjective how good quality you wanted bro. To achieve high end SQ setup is expensive hobby actually. If you always with drive with family & you wants ur family also enjoy good quality sound.. u would consider powering rear speaker also. Remember you need DSP with more channels.

first car : Crossfire A6XS - build in 4 channel amp, 8 rca output

second car : Rockpower 10.8 - build in 8 channel amp , 10 rca output.

both below 2k including installations & tuning.