If you can find a clean, functional PXA-H800 and RUX-C800 on the used market ($400–$700), it still rivals modern DSPs costing over $1,000. The 21-band parametric EQ gives you surgical control that most $500 processors lack. The optical input ensures a noise-free signal from digital sources.
However, if you are building a new system today and want wireless tuning via Bluetooth from your iPhone, look at the Alpine PXE-C60-88. It is newer, smaller, and supported. But for pure, warm, analog-sounding digital processing with the legendary "Imprint" auto-tune? The Sound Manager 21 remains an unmounted champion.
If you need a 21-band parametric EQ, optical input, and the ability to fully flatten a hostile factory radio signal, the Alpine Imprint Sound Manager 21 (PXA-H800) is the holy grail of discontinued car audio processors.